Ability to create, edit, delete LLMs

[krschacht]

There will be a few built-in LLMs such as GPT-3.5, GPT-4, and the Claude ones. But in addition people may want to create their own LLM, just for themselves, which can be configured to point to any arbitrary URL, port. For now I think we can assume that it will always conform to OpenAI’s API since most people seem to be imitating that.