[Feature] Add favorite models & customize list of models for each provider

[oooskarrr]

Problem Description
I think the way we currently choose and switch between models is not intuitive at all, and needs to be improved.

Proposed Solution
Ideally, one should be able to edit the list of models for each provider. Some of the lists are massive, for example Google's and OpenAI's lists contain dozens of models. It would be nice if one could get rid of (either delete, or temporarily deactivate) all the models one doesn't use.

Alternatively, you could implement a way to set certain models as "favorites", and one should be able to easily switch between models (even mid-conversation) by simply choosing among the favorites in a dropdown menu. Just like in the screenshot below:

By the way, how is it currently determined which models get displayed in this dropdown menu? It seems completely random. It would be great if we could specifically choose which models from which providers get listed in this dropdown menu.

Thank you in advance for considering implementing this.

Cheers :)