Add mixed surfaces stub and tests

1. Add a new test stub with two SurfaceView and two TextureView
2. Add the following tests
2-1. Single TextureView preview
2-2. Single TextureView preview with one ImageReader
2-3. Dual TextureView preview
2-4. Dual TextureView preview with one ImageReader

Change-Id: I0b8c69cdfed4e3fca0c8865fc5f43a70794e711c
6 files changed