Bugzilla to Gitlab Markdown generation script

• cc: @boklm @brizental @clairehurst @dan @henry @jwilde @ma1 @pierov
• cc: @thorin @bella

I'm no shell-script expert, but it does the job. For the actual audit issues I'll need to dump the <details> sections into separate comments as gitlab falls over with too much 'complicated' markdown in a single post.

Example output in a subsequent commemnt.