Restrict model selection per feature

Problem

Currently we allow any registered model to be selected for either Code Generations and Code Completions. But some models can’t do both functions, e.g.: Mistral. So even though the user can select this model through the UI, it will have no effect. In this case it is an even bigger problem since the self-hosted user expects its data to be sent to its own local model, not Anthropic (or whatever LLM provider we are currently using).

example: mistral shouldn't be allowed to be selected for Code Completions

Proposal

We only show compatible self-hosted models within the model selection drop-down.