fakehwc, libvr_hwc-hal: ComposerClient is moved

ComposerClient is moved to another library with some changes.  This
allows us to kill the has-a relation between VrComposerClient and
ComposerClientImpl in VR.

Test: builds
Change-Id: I0c32386f7d62f33e2e4d1271be42953f6880fd75
8 files changed