GraphicsEnv: Get feature overrides from GpuService

Query GpuService for the latest ANGLE feature overrides and store them
in GraphicsEnv. This must be done separately, because Zygote cannot
perform Binder calls and GraphicsEnv must be able to handle being called
at Zygote creation and App launch. This also helps minimize the boot time
impact of this feature.

Bug: 372694741
Test: CQ, Manual verification
Flag: com.android.graphics.graphicsenv.flags.feature_overrides
Change-Id: I9bfd295e57593074262a77fc8e2abe91b5d18791