Regenerate GenerateContent data models from Google Discovery Document
revision 20261019 to resolve drift detected by check-data-models CI,
and move server-side tool invocations into Part.PartData.
Data model updates:
- Candidate.FinishReason: Add continuation case for per-request limits.
- Candidate & GenerateContentRequest: Add continuationToken as String
to round-trip opaque tokens without strict base64 decoding.
- GenerateContentRequest: Add outputConfig for Cloud Storage media
persistence (GenerateContentRequestOutputConfig).
- Part: Add toolCall and toolResponse to oneOf definitions in
firebasevertexai-overrides.yaml and map to Part.PartData variants,
removing top-level stored properties to preserve the invariant that
every Part has data.
Tooling:
- Fix 'swift format' invocation on CI.
