Reland: [Workflow] Add new code format helper.

I landed this format helper, but unfortunately, it didn't work because
of permissions, it could not add comments on a fork's PR. @cor3ntin
informed me there are fixes for this that you had worked on @tstellar -
but I didn't have time to read up on it too much. Can you explain what
changes are needed to get the action to be able to write comments on
fork's PR?