configstore: remove build flags from surfaceflinger

This change removes build flags used in building surfaceflinger.
Instead, surfaceflinger uses android.hardware.configstore HAL to get
values for the build flags at runtime.

As a first attempt, a build flag VSYNC_VENT_PHASE_OFFSET_NS is converted
to a hwbinder call to vsyncEventPhaseoffsetNs() function in
android.hardware.configstore@1.0 package.

Note that VSYNC_EVENT_PHASE_OFFSET_NS still remains in Android.mk
for non-treble targets.

Design doc: go/design-confighal
Bug: 34314793
Test: build, run, log message "Phase offset NS: ..." should be seen.

Change-Id: I43862d4df5abd3e9275ec9c0e2e0b568d8b48347