Extract an interface SurfaceCapture from ScreenEncoder, representing a video source which can be rendered to a Surface for encoding. Split ScreenEncoder into: - ScreenCapture, implementing SurfaceCapture to capture the device screen, - SurfaceEncoder, to encode any SurfaceCapture. This separation prepares the introduction of another SurfaceCapture implementation to capture the camera instead of the device screen. PR #4213 <https://github.com/Genymobile/scrcpy/pull/4213> Co-authored-by: Romain Vimont <rom@rom1v.com> Signed-off-by: Romain Vimont <rom@rom1v.com>