[RUM-16486] Fix DatadogContext not propagated to legacy FeatureMessageReceiver

Author: maxep

DatadogCore/Sources/Core/DatadogCore.swift

@@ -119,9 +119,10 @@ internal final class DatadogCore {
         // the bus will keep a weak ref to the core.
         bus.connect(core: self)
 
-        // forward any context change on the typed message-bus
+        // forward any context change on the message-bus
         self.contextProvider.publish { [weak self] context in
-            self?.bus.send(message: context)
+            self?.bus.send(message: context)                       // typed bus (new receivers)
+            self?.send(message: .context(context))       // legacy bus (receivers pending migration)
         }
     }
 
@@ -264,9 +265,8 @@ internal final class DatadogCore {
     ///   - key: The key associated with the receiver.
     private func add(messageReceiver: FeatureMessageReceiver, forKey key: String) {
         bus.connect(messageReceiver, forKey: key)
-        // Push current context to typed-bus DatadogContext subscribers.
         contextProvider.read { context in
-            self.bus.send(message: context)
+            self.bus.queue.async { messageReceiver.receive(message: .context(context), from: self) }
         }
     }