Use sysprops to control the creation of protected context.

Previously we create protected context as long as the extension exsists,
however, a lot of devices that get upgraded to Q won't have such support even
if they have this extension, and thus we add a new configuration to allow OEMs
to configure their devices based on hardware capabilities. If the property is
configured as false, then we won't create protected context.

BUG: 35315015
Test: Verify with Youtube and ExoPlayer with protected contents.
Change-Id: I3cc11081ea9457c35f2380d4361be47a03438746