feature: Add shader_mask property to the View class

[bl1nch]

Duplicate Check

• I have searched the opened issues and there are no duplicates

Describe the requested feature

If we add a shader_mask property to the View class on the Python side, we could parse it on the Dart side and wrap the internal Container (which View is built from) with a ShaderMask control, for example here:

flet/packages/flet/lib/src/controls/view.dart

Line 275 in 33ac583

result = Container(

This feature would be very useful when we want to apply a gradient shader in cases where View.decoration = BoxDecoration(image=DecorationImage()) is already specified.
Currently, if we set a Gradient inside BoxDecoration, the image is rendered on top of the gradient, making the gradient invisible.

Suggest a solution

No response

Screenshots

No response

Additional details

No response