Move GrBatchFlushState from GrDrawTarget to GrDrawingManager

This CL:
  moves the flushState
  disables immediate mode (it was proving difficult to implement)
  also moves the program unit test to the drawing manager

BUG=skia:4094
TBR=bsalomon@google.com

Review URL: https://codereview.chromium.org/1437843002
9 files changed