Use WidgetStateProperty instead of ButtonState

[bdlukaa]

Is your feature request related to a problem? Please describe.
Recently, the WidgetStateProperty class was added to the Flutter framework. It is a replacement to MaterialStateProperty and is intended to be used on other design systems, such as cupertino. This class can be used to handle the multiple states the widgets can get in the package.

Describe the solution you'd like
Replace ButtonState with WidgetStateProperty.

Describe alternatives you've considered
n/a

Additional context
https://api.flutter.dev/flutter/widgets/WidgetStateProperty-class.html