feature(go): add support for multiple model versions

[hugoaguirre]

Adding the support for multiple model versions and grouping the versions in the model metadata.

Gemini models being rendered in Dev UI frontpage

Model versions being grouped in the Dev UI

Playing around with gemini-1.5-flash-8b-latest

Checking raw request

Checklist (if applicable):

• PR title is following https://www.conventionalcommits.org/en/v1.0.0/
• Tested (manually, unit tested, etc.)
• Docs updated (updated docs or a docs bug required)

[hugoaguirre]

Hi @pavelgj, @apascal07

Let me know your opinion about this approach.
I wanted to keep the model definition as it previously was because I think it was very simple and verbose.

The only changes added were:

• Rewrote how the known models are defined in the plugins (adding a new struct named: ai.ModelDetails that encapsulates the model capabilities and its versions)
• ai.ModelMetadata was updated to add model versions so they can be grouped together

[apascal07]

How is this to be used in code? I don't see any way to reference the exact version I want to use in a generate call for example.

[hugoaguirre]

How is this to be used in code? I don't see any way to reference the exact version I want to use in a generate call for example.

Feedback addressed in the last commit

[apascal07]

Overall, looks good. There's an outstanding issue that you are indirectly (but not fully) touching upon here: #1744

It's unrelated to this PR but it might make sense to just combine it, or at least do it just for the versions field and save the rest for another PR.