Record and show last used date of SSH Keys

See merge request !8113

Addresses: Issue #13810

1. Adds a last_used_at attribute to the Key table/model
2. Update a key's last_used_at whenever it gets used
3. Display how long ago an ssh key was last used

Moved the members and groups to single option called members

Closes #25985

See merge request !8281

* master: (35 commits)
  Adds back removed class in merge request pipelines table
  Fix dropdown icon alignment
  Simplify HTML of mini pipeline graph and dropdown Creates individual html for dropdown Adds simplified  CSS for the new dropdown Removes old CSS Improves dropdown item in Chrome, Firefox and Safari Use SCSS variables for colors. Fix scss linter errors Adds animation when the stage is hovered. Adds back tooltip on dropdown toggle Fixes broken tests additional css changes to get more into direction of mockups
  Adds CHANGELOG entry
  Removes unneeded `window` declaration
  Decreases font-size on login page
  Ensure internal Gitlab::Git references use the namespace
  Absorb gitlab_git
  Fix review comments.
  Add spec for note edit and fix one commented spec.
  Review fixes.
  Use gl.utils.isInViewport and improve gl.utils.animateToElement.
  Make sure elements share the same scope
  Hide edit warning element when form reverted.
  Remove unnecessary styling came from merge conflicts.
  Fix single note edit form specs.
  Separate edit form in Changes and Discussions tab.
  Fix warning styling for responsive design.
  Fix task list for single edit note widget changes.
  Fix notes spec.
  ...

Explain why we have this monkey-patch

See merge request !8329

This controller is going to contain both the project members and groups options
for the settings gear.

Generated the route and modified the routing to point to the new members setting path