chore: natively format generated TS client libraries with Prettier

[shivanee-p]

This PR is the first step to add a CI linter check within the monorepo. This introduces native Prettier GTS formatting directly into the GAPIC TypeScript generator (gapic-generator-typescript) so all generated code has the same formatting.

Key Changes:

• Generator Logic (templater.ts): Integrated asynchronous prettier.format(...) using GTS rules (typescript parser, single quotes, trailing commas, mandatory semicolons).
• Testing Baselines Updates (baselines/): Updated all 800+ .baseline snapshot files to incorporate the new Prettier formatting structure, preventing failing baseline tests.
• Bazel Support (BUILD.bazel): Added "//:node_modules/prettier" to Bazel execution dependencies for transparent deployment support.

[gemini-code-assist]

Code Review

This pull request updates several generated client library files for the gapic-generator-typescript. The changes primarily involve formatting adjustments, such as adding missing dependencies (e.g., prettier), updating import statements, and improving code readability through better spacing and line breaks in generated code. There are no review comments to address.