Add the ability to manage AI image description models

[seanbudd]

Is your feature request related to a problem? Please describe.

Add the ability to download/enable/disable/remove other AI models for image description.
This work may be blocked on #18662 which would make it easier to add new models.

Describe the solution you'd like

An AI model manager that lists available models, with a similar UX to the add-on store.
Models should include:

• a brief description on what makes them different to other models
• the download size
• recommended min CPU
• recommended min GPU

You should be able to download and remove models.
It might also be worth being able to disable and enable models.

While this design should initially be for downloadable local models. It's worth considering if the manager should be able to be expanded to support adding online based models

Describe alternatives you've considered

No response

Additional context

the AI image description feature leaves a lot to be desired without a model manager, translations, and #18662 to lower memory usage

[harun-342]

Although there are plugins that can do this, please also allow Gemini integration, please.

[seanbudd]

@harun-342 - the current plan is to get local models working well first #18662 #19338, but once this ticket is done, it should be relatively easy to add support for cloud models in separate PRs