Use buf-action in CI

[emcfarlane]

This PR updates CI to use the new buf-action replacing buf-setup, buf-lint, buf-breaking and buf-push unifying these tasks as one. The new behaviour is as follows:

• On pull requests: run build, lint, format and breaking change detection checks.
• On push: build and then push the changes of the latest commit with the label of the current branch (e.g. main).
• On delete: archive the label associated with the delete (e.g. the branch name of the PR).

Changes in behaviour:

• Checks no longer block pushes of commits to the BSR.
• Formatting check has been added in addition to lint and breaking.

[github-actions]

The latest Buf updates on your PR.

Name	Status
build	✅ passed
lint	✅ passed
format	✅ passed
breaking	✅ passed