[Tab Management] Add close all modal dialog to Incognito

Adds the Close All Tabs Modal Dialog warning to the Close all tabs
action on the Incognito tab switcher overflow menu.

Re-uses the non-Incognito component with different UX approved strings.

Added related unit tests. Integration test to follow.

Bug: 1287281
Change-Id: I67771ad9715a478a9d63f46a7d00723572693e4d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3450830
Reviewed-by: Yashar Dabiran <yashard@chromium.org>
Reviewed-by: Fred Mello <fredmello@chromium.org>
Auto-Submit: Calder Kitagawa <ckitagawa@chromium.org>
Reviewed-by: David Trainor <dtrainor@chromium.org>
Commit-Queue: Calder Kitagawa <ckitagawa@chromium.org>
Cr-Commit-Position: refs/heads/main@{#969940}