Use GraphQL to save/update a history note comment for a vulnerability

When viewing an individual vulnerability on the security dashboard, at the bottom of a page is a list of history notes that shows changes to the vulnerability state:

A comment can be added to a note. Currently, the comment is saved using a REST endpoint. We need to use GraphQL instead. To generate a note so that you can add a comment to it, change the status of the vulnerability at the top of the page using the dropdown:

See Design Issue and parent Epic for details.

Implementation Plan

• Update saveComment() in ee/app/assets/javascripts/vulnerabilities/components/history_comment.vue to use GraphQL. Verify that it works for both saving new notes and updating existing notes.