No support for use of FontAwesome (font) for icons

[msivers]

Would be great if this control supported FontImageSource for icons in the same way as Xamarin.Forms 4.... would love to use FontAwesome as used everywhere else in my app.

[LeoJHarris]

@msivers Hi, I am also adopting Fonts so I will look into implementing this, would be a good feature to have.

[mhrastegari]

i was just about to write an Enhacement for it

[LeoJHarris]

@mhrastegary77 PR's are welcome.

[LeoJHarris]

Theres a couple of tickets on this repo, just struggling to find time to get around to closing them.