Add route match for commit comments

[glensc]

Example:

• https://gitlab.com/gitlab-org/gitlab/-/commit/695c29abcf7dc2eabde8d59869abcea0923ce8fa#note_334686748

[glensc]

requires gitlab api client support to be able to fetch commit comments:

• https://docs.gitlab.com/ee/api/discussions.html#get-single-commit-discussion-item
• https://github.com/m4tthumphrey/php-gitlab-api/issues/347#issuecomment-621918201

[glensc]

funnily the documentation to the endpoint I'm using did not even exist:

• https://gitlab.com/gitlab-org/gitlab/-/merge_requests/30926