Add `google_aistudio` for generative configs

[databyjp]

For:

• Collection configs
• Runtime generative configs

See:

• https://github.com/weaviate/typescript-client/blob/main/src/collections/configure/generative.ts#L267
• https://github.com/weaviate/typescript-client/blob/main/src/collections/generate/config.ts#L267

See: https://weaviate-org.slack.com/archives/C07H95BUWKE/p1763556831801089?thread_ts=1763555951.215839&cid=C07H95BUWKE