[Reland] Implement Mandatory Reauth confirmation bubble.

This reverts commit 8dcd1b17 and
updates mandatory_reauth_bubble_view_uitest.cc such that it casts
the views properly.

Bug: 1427216
Change-Id: I70a1efc8202f36a5bf0ba22e16bbcd48bf652b05
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4562532


Reviewed-by: Vinny Persky <vinnypersky@google.com>
Commit-Queue: Justin Wells <justinleewells@google.com>
Reviewed-by: David Trainor <dtrainor@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1151383}