Variable refresh rate for virtual display

Allow virtual display to request a refresh rate, so it can be different
from VSYNC frequencies. SurfaceFlinger drops frames for the
corresponding virtual display based on the refresh rate.

Bug: 241286579
Test: atest libgui_test libsurfaceflinger_unittest SurfaceFlinger_test
Change-Id: I4fba0e553618bb4c7333514b16206ae4277acf72
11 files changed