Reduce dependency on Bitmap for Azure

[Webreaper]

Read image directly from file stream: https://stackoverflow.com/questions/58452830/await-faceclient-face-detectwithstreamasync-returning-null

Crop images for faces using ImageSharp.

When we call AzureFaceService SaveFaceThumb, we should a) put it in the thumb cache and b) use the GetFaceThumbNail method in the thumbService class