feat(magnify_ime): Add Option to Magnify Navigation Bar and IME [1/2]

Users who use screen magnifier now have the option to magnify
their navigation bar and IME (e.g. keyboard). We implement this through
a new Secure Setting monitored through the WindowManagerService,
which can be toggled by a user in the Settings.

Bug: 342509709
Flag: com.android.server.accessibility.enable_magnification_magnify_nav_bar_and_ime
Test: manually Navigate to Settings > Accessibility > Magnification
and turn on Magnify Navigation Bar and Keyboards .
Test that the navigation bar and keyboard can be magnified
depending on the setting. Turn the setting off, and the nav bar
and keyboard should not be magnifiable.
Test: atest WindowStateTests
(cherry picked from https://android-review.googlesource.com/q/commit:f8e9a266df16ac2a1f6f5ac525d6b9a490ab94fb)

Change-Id: I5496bcd9b5c3cf94620eedc7c86d12f31e86889a