[GPT] Add advanced configuration

[SEVENID]

To begin with, I would like to remind you that now the boom of large language models and even openAI provides access to several different "smartness". It is also unknown exactly how openAI uses our data. It would be great to be able to use other models with other apis and prompts. But first, we need the ability to change the endpoint to openAI and model parameters: some AI providers (for example, oobabooga / text-generation-webui ) can mimic openAI api.