User refresh rate for external display

Previously smoothdisplay and force
peak refresh rate were applied to
external displays. This is incorrect
because external displays need to have
stable and predictable refresh rate.
e.g. configured to be around 59-61hz.

This cl also uses user-preferred display
mode for external displays to set
the SizeAndPhysicalRefreshRatesRange.

Test: atest DisplayModeDirectorTest DisplayObserverTest
Change-Id: I1ee3a1cc007fe913a75099397f4f482a6af1202d
Bug: 370657357
Bug: 372026069
Flag: com.android.server.display.feature.flags.enable_user_refresh_rate_for_external_display