Add access requests selector

[gzdunek]

Closes #46223
Part 2/2 of the access requests selector.

Summary of changes:

• The access requests navigation items were moved from the additional actions menu to their own menu.
• The assumed roles bar was removed. Instead, we have a more subtle button in the status bar.
  • While working on it, I removed the custom functions that formatted roles duration. Instead, I used formatDistanceToNow from date-fns, I think the output is much nicer.
• The access requests menu is now the central place to assume/drop access requests.

Demo:

demo.mov

changelog: Teleport Connect now features a new menu for quick access request management