Add support for event loop to over come memory leak errors by CI

```
Changes Added : Added event loop support in test code

problem : After adding support for sending events from phosphor-user-manager it is obsderved that it is calling sendEvent which internally calls async_send_handler and allocates memeory for context
since the event loop is not present in test code, callback is never called and
the CI was throwing memory leak error

Direct leak of 1 byte(s) in 1 object(s) allocated from:
    #0 0x7ffa787b91e7 in operator new(unsigned long) ../../../../src/libsanitizer/asan/asan_new_delete.cpp:99
    openbmc#1 0x7ffa77ad6383 in operator() /usr/local/include/sdbusplus/asio/detail/async_send_handler.hpp:40
    openbmc#2 0x7ffa77ad6383 in async_send<sdbusplus::asio::connection::async_method_call_timed<phosphor::logging::sendEvent(phosphor::logging::MESSAGE_TYPE, sdbusplus::xyz::openbmc_project::Logging::server::Entry::Level, const std::vector<std::__cxx11::basic_string<char> >&, const string&)::<lambda(boost::system::error_code)>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::map<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::less<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<const std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > > >
    (phosphor::logging::sendEvent(phosphor::logging::MESSAGE_TYPE, sdbusplus::xyz::openbmc_project::Logging::server::Entry::Level, const std::vector<std::__cxx11::basic_string<char> >&, const string&)::<lambda(boost::system::error_code)>&&, const string&, const string&, const string&, const string&, uint64_t, const std::__cxx11::basic_string<char>&, const std::__cxx11::basic_string<char>&, const std::map<std::__cxx11::basic_string<char>, std::__cxx11::basic_string<char> >&)::<lambda(boost::system::error_code, sdbusplus::message_t&)> > /usr/local/include/sdbusplus/asio/connection.hpp:98
    openbmc#3 0x7ffa77ad6383 in async_method_call_timed<phosphor::logging::sendEvent(phosphor::logging::MESSAGE_TYPE, sdbusplus::xyz::openbmc_project::Logging::server::Entry::Level, const std::vector<std::__cxx11::basic_string<char> >&, const string&)::<lambda(boost::system::error_code)>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::map<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::less<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<const std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > > > /usr/local/include/sdbusplus/asio/connection.hpp:192
    openbmc#4 0x7ffa77ad6383 in async_method_call<phosphor::logging::sendEvent(phosphor::logging::MESSAGE_TYPE, sdbusplus::xyz::openbmc_project::Logging::server::Entry::Level, const std::vector<std::__cxx11::basic_string<char> >&, const string&)::<lambda(boost::system::error_code)>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::map<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::less<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<const std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > > > /usr/local/include/sdbusplus/asio/connection.hpp:221
    openbmc#5 0x7ffa77ad6383 in phosphor::logging::sendEvent(phosphor::logging::MESSAGE_TYPE, sdbusplus::xyz::openbmc_project::Logging::server::Entry::Level, std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) ../lib/redfish_event_log.cpp:112
    openbmc#6 0x55dfba9084a3 in phosphor::certs::Manager::replaceCertificate(phosphor::certs::Certificate*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) ../certs_manager.cpp:493
    openbmc#7 0x55dfba8ab09d in phosphor::certs::Certificate::replace(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) ../certificate.cpp:315
    openbmc#8 0x55dfba7981e0 in TestBody ../test/certs_manager_test.cpp:677
    openbmc#9 0x7ffa786e3f2e in void testing::internal::HandleSehExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) /googletest-662fe38e44900c007eccb65a5d2ea19df7bd520e/googletest/src/gtest.cc:2607
    openbmc#10 0x7ffa786e3f2e in void testing::internal::HandleExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) /googletest-662fe38e44900c007eccb65a5d2ea19df7bd520e/googletest/src/gtest.cc:2643

```

Solution : The memory leak error was thrown because the
memory allocated by "async_send_handler" in sdbusplus was not getting de-allocated
because the callback is never getting called called since there was no event loop
present in test code.

Added event loop support in test code

Fixes jira https://jirasw.nvidia.com/browse/DGXOPENBMC-8881

Author: Chandramohan Harkude

test/ldap_config_test.cpp

@@ -60,6 +60,21 @@ class TestLDAPConfig : public testing::Test
         fs.close();
     }
 
+    void eventLoop(uint8_t numberOfTimes)
+    {
+        if (numberOfTimes == 0 || numberOfTimes > 15)
+        {
+            return;
+        }
+
+        for (int i = 0; i < numberOfTimes; i++)
+        {
+            bus.process_discard();
+            // wait for 1 seconds
+            bus.wait(1 * 1000000);
+        }
+    }
+
     void TearDown() override
     {
         fs::remove_all(dir);
@@ -461,7 +476,8 @@ TEST_F(TestLDAPConfig, testSearchScope)
         "MyLdap12", ldap_base::Create::SearchScope::sub,
         ldap_base::Create::Type::ActiveDirectory, "attr1", "attr2");
     managerPtr->getADConfigPtr()->enabled(true);
-
+    // Process D-Bus calls
+    eventLoop(6);
     // Change LDAP SearchScope
     managerPtr->getADConfigPtr()->ldapSearchScope(
         ldap_base::Config::SearchScope::one);
@@ -618,7 +634,8 @@ TEST_F(TestLDAPConfig, ConditionalEnableConfig)
 
     EXPECT_EQ(managerPtr->getADConfigPtr()->enabled(), true);
     EXPECT_EQ(managerPtr->getOpenLdapConfigPtr()->enabled(), false);
-
+    // Process D-Bus calls
+    eventLoop(5);
     // AS AD is already enabled so openldap can't be enabled.
     EXPECT_THROW(
         {
@@ -641,6 +658,8 @@ TEST_F(TestLDAPConfig, ConditionalEnableConfig)
     EXPECT_EQ(managerPtr->getOpenLdapConfigPtr()->enabled(), false);
     // Now enable the openldap
     managerPtr->getOpenLdapConfigPtr()->enabled(true);
+    // Process D-Bus calls
+    eventLoop(5);
     EXPECT_EQ(managerPtr->getOpenLdapConfigPtr()->enabled(), true);
     EXPECT_EQ(managerPtr->getADConfigPtr()->enabled(), false);
 
@@ -678,6 +697,8 @@ TEST_F(TestLDAPConfig, createPrivMapping)
             }
         },
         PrivilegeMappingExists);
+    // Process D-Bus calls
+    eventLoop(2);
 }
 
 TEST_F(TestLDAPConfig, deletePrivMapping)
@@ -719,6 +740,8 @@ TEST_F(TestLDAPConfig, deletePrivMapping)
     EXPECT_NO_THROW(manager.getADConfigPtr()->checkPrivilegeMapper("admin"));
     manager.getADConfigPtr()->deletePrivilegeMapper(2);
     EXPECT_NO_THROW(manager.getADConfigPtr()->checkPrivilegeMapper("user"));
+    // Process D-Bus calls
+    eventLoop(2);
 }
 
 TEST_F(TestLDAPConfig, restorePrivMapping)
@@ -798,6 +821,8 @@ TEST_F(TestLDAPConfig, testPrivileges)
 
     EXPECT_NO_THROW(entry->privilege("priv-operator"));
     EXPECT_NO_THROW(entry->privilege("priv-user"));
+    // Process D-Bus calls
+    eventLoop(5);
 }
 
 } // namespace ldap

test/ldap_mapper_test.cpp

@@ -33,6 +33,20 @@ class TestSerialization : public testing::Test
         char tempDir[] = "/tmp/privmapper_test.XXXXXX";
         dir = std::filesystem::path(mkdtemp(tempDir));
     }
+    void eventLoop(uint8_t numberOfTimes)
+    {
+        if (numberOfTimes == 0 || numberOfTimes > 15)
+        {
+            return;
+        }
+
+        for (int i = 0; i < numberOfTimes; i++)
+        {
+            bus.process_discard();
+            // wait for 1 seconds
+            bus.wait(1 * 1000000);
+        }
+    }
 
     void TearDown() override
     {
@@ -139,6 +153,8 @@ TEST_F(TestSerialization, testValidPrivilege)
 
     EXPECT_NO_THROW(entry->privilege("priv-operator"));
     EXPECT_NO_THROW(entry->privilege("priv-user"));
+    // Process D-Bus calls
+    eventLoop(5);
 }
 
 TEST_F(TestSerialization, testInvalidPrivilege)