feat: add actor token interpolation for comments

[sparten11740]

Summary

The code of this action was (and still is in large parts) quite filthy. I extracted and cleaned up a few things that I touched to at least achieve a little bit of structure.

Main goal of this PR is to enable token interpolation in comment strings provided to the action. So far <%= author %> is supported. Example usage:

- name: Label PRs
  uses: './actions-label-merge-conflict'
  with:
    dirtyLabel: 'blocked/needs-rebase'
    repoToken: '${{ secrets.GITHUB_TOKEN }}'
    commentOnDirty: 'Houston, this is Conflict Bot. We have a conflict. @<%= author %> please rebase. Acknowledge.'
    retryAfter: 45

Testplan

Successfully tested in https://github.com/ExodusMovement/lerna-version-selectively/pull/135 by setting ref of the action to checkout this repo to this PR's branch (sparten11740/feat/add-placeholder-interpolation-to-messages)

Further comments

• The build output is checked in under dist/index.js. No need to review the file.
• The code formatting styles are really weird, I will add our linting/formatting rules in a follow up PR

[mvayngrib]

utACK

[mvayngrib]

don't leave me hanging man, did he rebase it in the end?

[andrejborstnik]

https://github.com/brucewayne will love this if we opensource hydra 🤣 (but please keep it)

[sparten11740]

what a shame that such a prestigious handle is wasted on a completely inactive account...

[andrejborstnik]

utACK