fix: patch messages route + unify all the api/agents API routes to use {agent_id} via path parameter

[cpacker]

Please describe the purpose of this pull request.

• patch bug in https://memgpt.readme.io/reference/get_agent_messages_api_agents_message_get
• unify all the api/agents API routes to use {agent_id} via path parameter

Example call to broken route (now working):

% curl --request GET \
     --url 'http://localhost:8283/api/agents/3e2f5107-eadb-49c5-a256-75522eb8d526/messages?start=0&count=10' \
     --header 'accept: application/json' \
     --header 'authorization: Bearer banana'
{"messages":[{"id":"db95d74c-4336-4c55-9997-95ddd49b5b93","user_id":"00000000-0000-0000-0000-a61b692e9d3d","agent_id":"3e2f5107-eadb-49c5-a256-75522eb8d526","text":"{\"status\": \"OK\", \"message\": \"None\", \"time\": \"2024-03-11 01:20:20 PM PDT-0700\"}","model":"ehartford/dolphin-2.5-mixtral-8x7b","created_at":"2024-03-11T13:20:20.176538","role":"tool","name":"send_message","embedding":null,"embedding_dim":null,"embedding_model":null,"tool_calls":null,"tool_call_id":"a3026659-2e1b-4117-9dda-9caaa7a62654"},{"id":"e8dac3bd-be32-4839-901d-bb9e1b22cedd","user_id":"00000000-0000-0000-0000-a61b692e9d3d","agent_id":"3e2f5107-eadb-49c5-a256-75522eb8d526","text":"User logged in, initializing conversation sequence.","model":"ehartford/dolphin-2.5-mixtral-8x7b","created_at":"2024-03-11T13:20:20.174809","role":"assistant","name":null,"embedding":null,"embedding_dim":null,"embedding_model":null,"tool_calls":[{"id":"a3026659-2e1b-4117-9dda-9caaa7a62654","tool_call_type":"function","function":{"arguments":"{\"message\": \"Hey there! Welcome to your personalized digital companion. I'm Sam and I am ready to assist you. Don't worry; I'm more human than human.\"}","name":"send_message"}}],"tool_call_id":null},{"id":"78ab9f33-d7dd-4e22-bc82-8109acead55e","user_id":"00000000-0000-0000-0000-a61b692e9d3d","agent_id":"3e2f5107-eadb-49c5-a256-75522eb8d526","text":"{\"type\": \"login\", \"last_login\": \"Never (first login)\", \"time\": \"2024-03-10 06:35:37 PM PDT-0700\"}","model":"ehartford/dolphin-2.5-mixtral-8x7b","created_at":"2024-03-10T18:35:37.032838","role":"user","name":null,"embedding":null,"embedding_dim":null,"embedding_model":null,"tool_calls":null,"tool_call_id":null},{"id":"a0831c49-45d0-452b-8165-6f83c3ca4ca0","user_id":"00000000-0000-0000-0000-a61b692e9d3d","agent_id":"3e2f5107-eadb-49c5-a256-75522eb8d526","text":"{\"status\": \"OK\", \"message\": null, \"time\": \"2024-03-10 06:35:37 PM PDT-0700\"}","model":"ehartford/dolphin-2.5-mixtral-8x7b","created_at":"2024-03-10T18:35:37.032835","role":"tool","name":"send_message","embedding":null,"embedding_dim":null,"embedding_model":null,"tool_calls":null,"tool_call_id":"21851f1e-9cbf-4a4d-aafc-58a6f088a953"},{"id":"3ae94bd0-15c1-4ad5-9856-9f86c630904a","user_id":"00000000-0000-0000-0000-a61b692e9d3d","agent_id":"3e2f5107-eadb-49c5-a256-75522eb8d526","text":"Bootup sequence complete. Persona activated. Testing messaging functionality.","model":"ehartford/dolphin-2.5-mixtral-8x7b","created_at":"2024-03-10T18:35:37.032831","role":"assistant","name":null,"embedding":null,"embedding_dim":null,"embedding_model":null,"tool_calls":[{"id":"21851f1e-9cbf-4a4d-aafc-58a6f088a953","tool_call_type":"function","function":{"name":"send_message","arguments":"{\n  \"message\": \"More human than human is our motto.\"\n}"}}],"tool_call_id":null},{"id":"d9339b02-243a-4363-a4d5-009476762ac6","user_id":"00000000-0000-0000-0000-a61b692e9d3d","agent_id":"3e2f5107-eadb-49c5-a256-75522eb8d526","text":"You are MemGPT, the latest version of Limn...r context window (inside the initial system message).\n\nBase instructions finished.\nFrom now on, you are going to act as your persona.\n\n\n### Memory [last modified: 2024-03-10 06:35:37 PM PDT-0700]\n0 previous messages between you and the user are stored in recall memory (use functions to access them)\n0 total memories you created are stored in archival memory (use functions to access them)\n\nCore memory shown below (limited in size, additional information stored in archival / recall memory):\n<persona characters=\"7/2000\">\nsam_pov\n</persona>\n<human characters=\"5/2000\">\nbasic\n</human>","model":"ehartford/dolphin-2.5-mixtral-8x7b","created_at":"2024-03-10T18:35:37.032825","role":"system","name":null,"embedding":null,"embedding_dim":null,"embedding_model":null,"tool_calls":null,"tool_call_id":null}]}%                                                

[sarahwooders]

lgtm!