Decouple SurfaceTexture from HWUI

Remove all Skia and HWUI types from SurfaceTexture
implementation.
Move SurfaceTexture to libgui (ag/9578265).
Define private C++ API for SurfaceTexture, which is consumed
by DeferredLayerUpdater.
Move AutoBackendTextureRelease/Skia code from SurfaceTexture
to HWUI.

Test: pass CtsUiRenderingTestCases and CtsViewTestCases
Bug: 136263580
Change-Id: I3f971bb490f64a3ac0b2a66a89ba935bf7f08213