Add attribution and onboarding commands to conversation and Almond (#28621)

* Add attribution and onboarding commands to conversation and Almond

* False -> None

* Comments

* Update __init__.py

* Comments + websocket for convert

* Lint

homeassistant/components/conversation/agent.py

@@ -8,6 +8,19 @@ from homeassistant.helpers import intent
 class AbstractConversationAgent(ABC):
     """Abstract conversation agent."""
 
+    @property
+    def attribution(self):
+        """Return the attribution."""
+        return None
+
+    async def async_get_onboarding(self):
+        """Get onboard data."""
+        return None
+
+    async def async_set_onboarding(self, shown):
+        """Set onboard data."""
+        return True
+
     @abstractmethod
     async def async_process(
         self, text: str, conversation_id: Optional[str] = None