Vulnerability Dismissal Types / Reasons
## Proposal
1. Provide users a way to quickly select a predefined reason for dismissing a vulnerability.
1. Provide users with a way to track/audit vulnerability dismissal exemptions.
1. Extend the ability of selecting a reason beyond the Vulnerability Report to other key areas of vulnerability interaction.
Additional details can be found in the design issue: https://gitlab.com/gitlab-org/gitlab/-/issues/196976

### Dependencies
The project uses components being developed for the &5629+ project that is set to be enabled by default in 16.0. This means that self-managed customers will not have access to this feature by default until then. Please contact us if you would like to use this feature in %15.11.
1. SaaS/gitlab.com - planning for %"15.11"
2. Self-managed customers - planning for %"16.0"
### Technical Details
Today the dismissal reason & the comment are stored in the same DB field. In order to enable tracking/auditing, the dismissal reason should be stored in a dedicated datapoint.
#### Engineering DRI for this Epic
- ~backend: @ghavenga
- ~frontend: @lorenzvanherwaarden
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