feat: workflow to automatically update java format + create PR

[russellwheatley]

• Adds a cron job GitHub Actions workflow that checks for new google-java-format releases, updates the bundled JAR in lib/, rewrites the hardcoded JAR path in index.js, runs ./test.sh, and opens a PR automatically when an upstream update is available.
• Also adds workflow_dispatch to the existing test workflow so CI can be run manually on the generated update branch/PR without requiring a PAT.
• pin all actions to SHAs.

[gemini-code-assist]

Note

Gemini is unable to generate a review for this pull request due to the file types involved not being currently supported.

[mikehardy]

LGTM - hadn't seen the 'create-pull-request' action before

I see it's on version v8.1.0 now but I've got a task to go through and mitigate supply chain risks in the repos I manage, could we use SHAs for the actions here instead of version numbers, to mitigate the risk of the actions here changing out from under us ?

The sha for create-pull-request v8.1.0 is currently c0f553fe549906ede9cf27b5156039d195d2ece0 FWIW

We may want to set up dependabot for the repo as well, and it appears that dependabot can work with commit SHAs just fine

[russellwheatley]

@mikehardy - I've updated them all to use SHAs now 🙏

[mikehardy]

✨ clean