fix: made beliefs a dict of lists

[
    Before it was a list of a dict of lists of lists of strings
    now it is a dict of lists of lists of strings as prescribed by architecture (knowledge base)
    *also added some tests, but will have to add some more
]

[ref]: N25B-206

src/control_backend/agents/mock_agents/belief_text_mock.py

@@ -12,9 +12,8 @@ class BeliefTextAgent(Agent):
             # Send multiple beliefs in one JSON payload
             payload = {
                 "type": "belief_extraction_text",
-                "beliefs": [
-                    {"user_said": [["hello"],["Can you help me?"],["stop talking to me"],["No"],["Pepper do a dance"]]}
-                ]
+                "beliefs": {"user_said": [["hello","test"],["Can you help me?"],["stop talking to me"],["No"],["Pepper do a dance"]]}
+                
             }
 
             msg = Message(to=to_jid)