feat(js): add llama-3.2 support to model garden plugin

[huangjeff5]

Checklist (if applicable):

• [ x ] Tested (manually, unit tested, etc.)

[pavelgj]

Could you please make the same change to the next branch?

[pavelgj]

coud you please also update https://github.com/firebase/genkit/blob/main/docs/plugins/vertex-ai.md#llama-31-405b-on-vertex-ai-model-garden