Make model downloader available after initial setup

[bestlinuxgamers]

As far as I know, the automatic downloader for models is only available when the UI is started for the first time. It would be helpful to be able to use this later as well.

[mcmonkey4eva]

My plan for this is to eventually have "Ghost models" visible in the model listing showing various recommended core models (with of course the ability to remove it if you don't want it), that would enable having eg controlnets and etc listed and ready to use.

Maybe also an interface wherein you can simply paste a huggingface/civitai/whatever link and have it automatically download it to the right folder & ensure metadata/thumbnails/etc are set and all for convenience

[bestlinuxgamers]

These ideas sound really great. It would also be important for the ghost models to be easily visually distinguishable from already installed models and preferably separated by a gap.

I thought that a public repository, where the latest models and the corresponding download links are provided, could also be implemented. Theoretically, this could simply be done using a git repository with a json file. This would also allow developers of other custom checkpoints to bring their checkpoints directly into the UI (through a PR in this repo). If it were then possible to add custom repository URLs, third party developers could also offer experimental snapshots, for example.