Add MaterialButton TintColor Property?

**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.