gralloc: move gralloc2 code inside gralloc2

Move Gralloc2 code and types from GraphicBufferAllocator and
GraphicBufferMapper into Gralloc2.h/.cpp.

Bug: 120493579
Test: manual
Change-Id: I1268b0fd1a0645ce3dc4782a23d6d5fe83a4ba27
4 files changed