[CrOS Hotspot] Add hotspot detailed view controller

This CL adds the HotspotDetailedViewController class which contains the
logic to update the hotspot detailed page within the quick settings and
toggle on/off hotspot.

Bug: b/274154971
Change-Id: Ic6e5d22c9920cc21b9c50b3a4697a2fac42149b5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4540802


Commit-Queue: Jason Zhang <jiajunz@google.com>
Reviewed-by: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1145708}