Device-Specific Display Settings Should Not Be Applied During Tests

Many tests use the device display(s), which may have override
settings applied such as ignoring activity requested orientation.
These settings are read in DisplayWindowSettingsProvider. This CL
introduces TestDisplayWindowSettingsProvider, which uses in-memory
settings storage, ensuring that tests never read from display config
files and never write to them either, preventing changes made to
displays during tests from persisting.

Bug: b/182499175
Test: atest WmTests
Change-Id: Iee63f77a83057b709630e1d2c2cf8dfc3ba88200