[FR] add unit and system test via ament_add_gtest

[fujitatomoya]

Feature request

Feature description

Currently test needs to be started by manual procedure with different executable package named ros2_persistent_parameter_server_test.
The CI/CD test should be integrated into parameter_server package with ament_add_gtest, so that it can be tested with colcon test command for integration aligned with other ROS 2 packages.

Implementation considerations

• add test folder into parameter_server package with ament_add_gtest.
• move test contents from ros2_persistent_parameter_server_test to the test folder described above.
• all uncrustify warnings and coding style needs to be addressed.
• add colcon test --packages-select parameter_server in github workflow.