Remove libdvr platform library

In order to decrease boot class path pollution, let's move the VR
specific DVR native libraries into a public OEM library, which can be
directly loaded by 3P apps instead of needing to be loaded through
frameworks.

Bug: 111911841
Test: "lunch taimen_xr-userdebug; m -j64", side-load updated VrCore:
no regressions in booting directly to VR.

Change-Id: I1d40bcbafef0d54b3bf3a8ff574e77ae394435e9