Sam Beckham authored Jul 11, 2019 and Fatih Acet committed Jul 11, 2019

- Adds actions/mutations for commenting on a dismissed vulnerability in
the group security dashboard.
- Adds the same actions to the security reports
- Displays the comment box on a dismissed comment
- Sets the dismissal modal in the correct state when the comment box is
focused
- Adds snowplow tracking for dismissal comments

Once a vulnerability has been dismissed, anyone can now comment on it to
explain the dismissal reason.