Improve save functionality for ISP modules

[bakhtawar-10xe]

Currently save method works fine for modules that output an RGB image but the current output for modules in bayer raw and YUV do not visually depict the actual result

Module Output:
BLC (Bayer Raw)

Demosaic (RGB)

2DNR (YUV)

[marianadeem-10xe]

Updated the save method by the addition of the following two functions:

• added function raw_to_rgb in utils.py
  To save .png file for modules returning a bayer raw image, the raw image is first converted to RGB image by defining the 3 channels as shown below:
  
• added yuv_to_rgb function from RGBC to utils.py.
  To save .png file for modules returning a YUV image, yuv_to_rgb function is used to convert yuv image to rgb
  image before saving.

Module Output:
BLC (Bayer Raw)

Demosaic (RGB)

2DNR (YUV)