Add toggle to show/hide dismissed vulnerabilities

• Related issue: #9102 (closed)
• CE backport: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/32413

What does this MR do?

This adds a Hide dismissed toggle next to the filters in the security dashboard. This toggle lets users show or hide previously dismissed vulnerabilities. The toggle is enabled by default, which means that users will need to manually disable it in order to see dismissed vulnerabilities.

What does it look like?

Toggle behaviour

When the toggle is switched on or off, the vulnerabilities list is updated and an URL parameter is kept in sync with the toggle's state.

toggle_behaviour

Responsiveness

Here's what it looks like on all viewport sizes:

toggle_responsive

note: As of writing this, backend filter isn't fully implemented yet, which explains why the vulnerabilities don't change along with the toggle's state in the video.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
  • Doc MR: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/32674
• Code review guidelines
• Style guides
• Separation of EE specific content