Add Mahi menu settings button functionality.

Link the button to the Mahi settings page and record a metric when the
button is pressed.

Bug: b:331290853
Change-Id: I54c9d4687419cb9f74701903b4d225452b5eaac8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5446530
Reviewed-by: Crisrael Lucero <crisrael@google.com>
Commit-Queue: Michelle Chen <michellegc@google.com>
Reviewed-by: Thanh Nguyen <thanhdng@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Andre Le <leandre@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1286856}