ITS: move LSC map plotting to image_processing_utils.py

Other changes:
  match lens shading color scheme in
  developer.android.com/reference/android/hardware/camera2/CaptureResult#STATISTICS_LENS_SHADING_CORRECTION_MAP

Files affected:
  test_yuv_plus_raw.py
  image_processing_utils.py

Bug: 340586787
Testing: desktop with Pixel 8 rear camera
Change-Id: Ie3b8ec93274508c092fdb945244f2b150b9f6a10