Add workflow to delete url issues

[NoPlagiarism]

• Idea from this comment by @smac89: https://github.com/nelsontky/gh-pages-url-shortener/issues/43#issuecomment-731888013
• Using issue-moderator-action by tachiyomiorg
• URL regex by Matthew O'Riordan's. Can't find true source page
  • Then regex was json escaped
• When comment is new, workflow should leave a comment explaining where to create issues with urls mentioning #43 issue
• ReadMe has an instruction to disable this workflow, if user gonna use forked repository
• To close, issue title must contain url only, so issues like 87 with title github.io links fail shouldn't close

Cons:

• google.com kinda links don't work, only www.google.com
• If user is stupid enough to reopen - then issue leaves open
  • Why? Just in case If action goes wrong and it will close wrong issue