Revert "Revert "Add useVrFlinger() method to SurfaceFlinger ConfigStore""

This reverts commit 2877c167ff7119d0c119da7117febd322f90a8a7.

Add useVrFlinger() method to SurfaceFlinger ConfigStore, which is
used to ensure we only start vr flinger on Daydream ready devices.

Bug: 35885165

Test: Checked for "SurfaceFlinger UseVrFlinger" in the logs,
confirmed it only shows up for Daydream ready devices.

Change-Id: I839b650b63cd008de03feb4c771b330374bd0682
4 files changed