Add MaterialButton TintColor Property?

[fabcall]

Is your feature request related to a problem? Please describe. As of now, when you use a MaterialButton with an icon, the color of the text and the icon might be different, depending on image color. Sometimes one might want to use a tintable icon on default MaterialButton without having to generate a icon with a specific color.

Describe the solution you'd like I can think about two fair ways to solve this problem: (1) having the icon to inherit MaterialButton TextColorProperty; or (2) having a TintColorProperty which defaults to TextColor.

Describe alternatives you've considered For now, I'm using the MaterialIconButton with no text.

[DRKV333]

This would be really useful. The readme actually says:

Image - The icon to be displayed next to the button's label. The color of the icon will be based on the TextColor property value of the button.

https://github.com/Baseflow/XF-Material-Library/blame/develop/README.md#L199

So, is this a bug, or is the readme wrong? I've sort of made this work in my project by binding the Color of the FontImageSource I use as the image to the Button's TextColor. It works, as long as I don't disable the button. Cause then this issue comes up: https://github.com/xamarin/Xamarin.Forms/issues/6836