API: add file path and line number to note (comment) for a given merge request

Hi! It would be very useful for me if comment had two more properties: code line number and file path. GET /projects/:id/merge_requests/:merge_request_id/notes/:note_id.

Please, refer common question: https://forum.gitlab.com/t/how-can-i-get-commit-line-comments-discussions-using-the-api/3665