Add new model type to use custom OpenAI api compatible servers

[FlorianJoncour]

Describe your changes

I added a new model type similar to OpenAI, but with the possibility to define the API entry point and the model name in order to allow using custom OpenAI compatible servers like those of vllm or llama.cpp

Issue ticket number and link

Checklist before requesting a review

• I have performed a self-review of my code.
• If it is a core feature, I have added thorough tests.
• I have added thorough documentation for my code.
• I have tagged PR with relevant project labels. I acknowledge that a PR without labels may be dismissed.

Notes

Model settings are stored in chatgpt-custom.txt which contains 3 lines:

1. api key (backward compatiblity)
2. api base url
3. model name

A future release may use QSettings, Json library or any other to store these values in a dict for safety

[manyoso]

These other servers would all expose OpenAI compatible API then? Do you have a specific example you're testing with?

[FlorianJoncour]

I'm not sure to understand the question.

There is a whole bunch of software that uses the OpenAI API as a reference implementation.
For example:
xorbitai inference
llama.cpp (optionaly as a server)
llama-cpp-python
Openllm (alongside others)
Ray llm (alongside others)
vllm (alongside its own protocol)
and many others...

The subject of this pull request is the possibility of using GPT4all as a client of these softwares as it already does with OpenAI.

(I'm sorry if my english is poor, i'm not strong in foreign languages)

[cebtenzzre]

We should do something with this commented-out code - either remove it if it isn't needed, or uncomment it if it is.

[FlorianJoncour]

You're right.

Most implementations force the model name to match betwen the client and the server.
But In my own implementation, I prefer to leave this blank because I plan to serve only one model per instance, so the model name is not important.

So it is probably better to let the user choose.

[Dbz]

I think I'm asking for something that is a subset of this: #1955 🙏