Render grayscale images

[matt-goldman]

Is there a way to render an image in grayscale using Maui.Graphics? Similar to this: https://github.com/luberda-molinet/FFImageLoading/wiki/Transformations-Guide#grayscaletransformation

I've looked at the DrawImage method and couldn't see a way to do it there. I wonder if this would work by layering two instances of the image over each other and using the Saturation blend mode? (When the blend modes are implemented).