Create format_java.yml

[knjk04]

Summary of change

Add a GitHub action to format Java files to adhere to the Google Java style guide.

Pull request checklist

Please keep this checklist in & ensure you have done the following:

• [x] Read, understood and adhered to our contributing document.

  • [x] Ensure that you were first assigned to a relevant issue before creating this pull request (N/A)
  • [x] Ensure code changes pass all tests

• [x] Read, understood and adhered to our style guide. A lot of our code reviews are spent on ensuring compliance with our style guide, so it would save a lot of time if this was adhered to from the outset.

• [x] Filled in the summary, context (if applicable) and related issue section. Replace the square brackets and its placeholder content with your contents. For an example, see any merged in pull request

• [x] Set this pull request to 'draft' if you are still working on it

• [x] Resolved any merge conflicts

For any of the optional checkboxes (e.g. the screenshots one), still check it if it does not apply.

[stale[bot]]

Is this still relevant? If so, what is blocking it? Is there anything you can do to help move it forward?

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.