Add spotless support for *.gradle.kts files

[rlazo]

The more we cover by the formatter the better.

That being said, support for groovy is broken. I hit diffplug/spotless#1922 when trying to use groovyGradle formatting.

[github-actions]

📝 PRs merging into main branch

Our main branch should always be in a releasable state. If you are working on a larger change, or if you don't want this change to see the light of the day just yet, consider using a feature branch first, and only merge into the main branch when the code complete and ready to be released.

[github-actions]

Vertex AI Mock Responses Check ⚠️

A newer major version of the mock responses for Vertex AI unit tests is available. update_responses.sh should be updated to clone the latest version of the responses: v5.1

[google-oss-bot]

	1 Warning
⚠️	Did you forget to add a changelog entry? (Add the 'no-changelog' label to the PR to silence this warning.)

Generated by 🚫 Danger

[github-actions]

Test Results

 1 022 files  +2   1 022 suites  +2   35m 48s ⏱️ -26s
 5 809 tests +2   5 787 ✅ +2  22 💤 ±0  0 ❌ ±0 
11 703 runs  +4  11 659 ✅ +4  44 💤 ±0  0 ❌ ±0 

Results for commit 2f3421a. ± Comparison against base commit 99f4325.

[emilypgoogle]

Looks good, though the collapsed plugins blocks seem a bit odd, since it's expected to be edited with some regularity, I assume there's no way to change that though.