Diff which was reverted: https://phab.comm.dev/D7837
More info on why it was reverted: https://linear.app/comm/issue/ENG-3928/focustrap-causes-regressions-to-modals-in-landing
Added `fallbackFocus` option, which sets focus to div when there are no focusable elements inside the FocusTrap.
**Old description:**
We want to prevent users from focusing outside the modals. Added `focus-trap-react` library, to do that, and covered the modals that we use. Added `fallbackFocus` option, which sets focus to div when there are no focusable elements inside the FocusTrap.