Optimize the way the image processing filters are creating their Metal Textures

[himanshunaidu]

Example: GrayscaleToColorFilter
Currently, these filter objects are creating CGImage objects out of the CIImage objects, and then creating Metal Textures.
For performance improvements, one can directly use the PixelBuffers that back the CIImage objects to create the Metal Textures.

Take reference from the new MeshGPURecord objects in the following PR:
#326