fix: various patches for Azure support + strip Box

[cpacker]

Please describe the purpose of this pull request.

Fixes a few bugs with Azure in the v0.3 release:

• (azure) credentials were not being properly saved after being read during memgpt configure
• patch the credentials file (MemGPTCredentials) to contain the full set of Azure creds
  • A few were missing, eg embedding_deployment
• fix a key error that would occur during first message verification (with Azure only)
  • it looks like OpenAI (+LocalLLMs) return None for function_call, whereas Azure doesn't even return the field, which is why only Azure would throw a key error

As part of this PR, I refactored the repo to strip dependency on Box and instead use Pydantic models. This had already partially happened for local LLMs (used to return Box types, but now return Pydantic models), but now this is also the case for the OpenAI and Azure OpenAI calls.

TODOs for follow-up PRs:

• Strip Box from requirements
• Add better output during "Thinking..." to illustrate what's going on with message verification

How to test

Run memgpt configure to set up Azure, then run memgpt run (no runtime errors = success)

Have you tested this PR?

Yes, was able to reproduce the error in #980 + verify the patch

[sarahwooders]

lgtm!