Approve a PR by leaving "/lgtm" comment

[lugi0]

Description

This add a GHA to approve a PR when a user leaves a "/lgtm" comment

How Has This Been Tested?

Merge criteria:

• The commits are squashed in a cohesive manner and have meaningful messages.
• Testing instructions have been added in the PR body (for PRs involving changes that are not immediately obvious).
• The developer has manually tested the changes and verified that the changes work

[lugi0]

testing /lgtm

[github-actions]

The following are automatically added/executed:

• PR size label.
• Run pre-commit
• Run tox

Available user actions:

• To mark a PR as WIP, add /wip in a comment. To remove it from the PR comment /wip cancel to the PR.
• To block merging of a PR, add /hold in a comment. To un-block merging of PR comment /hold cancel.
• To mark a PR as approved, add /lgtm in a comment. To remove, add /lgtm cancel.
  lgtm label removed on each new commit push.
• To mark PR as verified comment /verified to the PR, to un-verify comment /verified cancel to the PR.
  verified label removed on each new commit push.

Supported labels

{'/wip', '/verified', '/hold', '/lgtm'}

[lugi0]

see lugi0#2 for testing of the workflow

[rnetser]

please add condition to trigger only if "lgtm in comment"
e/g

    if: |
      contains(github.event.comment.body, '/lgtm')

also should be triggered on edited

[lugi0]

The actions already checks if /lgtm is int he comment: https://github.com/opendatahub-io/opendatahub-tests/pull/153/files#diff-8adeafbcbe79cc05a3ae753fd95a88451697a3356e53b468f8a7f565c5c737d1R13
Why would we edit a comment to add a lgtm? that seems unlikely to be honest

[rnetser]

1. i think adding the check on the content of the comment at the top makes it more clear
2. a user can edit a comment and add "lgtm"