Rely on emoji award to get the faulty spam comment

Some times, the spam is not a brand new issue, but a comment in the issue/MR/snippet.

damspam is currently ignoring those, but maybe we can "tag" the faulty comment ("note" as per gitlab definition) by adding an emoji award (💩 or 🚯 for example).

Basically, we need damspam to:

• check for the provided URL:
  • if the URL points at an issue or a MR, ensures the Spam label is present
  • if it's a new issue/snippet and the user is new -> do the usual stuff
  • if not:
    • look for every comment (note), and their emoji award, if there is one and the user is new, overwrite the comment with [edited: spam by @spambot], and block the user

We can then configure the webhooks to be executed on emoji webhooks, or manually in case it's a snippet on a personal project.