feat(comments): notify collaborators when adding a comment - #580

⚠️ Doistbot reviewed an earlier commit (452c3e5).

Original result: 7 findings (4 P2, 3 P3)

Inline review comments from the original run are still on this PR; they were against the prior commit and may not reflect the current diff. Comment @doistbot /review to re-run against the latest commit.