Custom shader for Bevy UI

[Tam]

Is it possible to replace the shader used in Bevy UI for a custom one?

I've tried overwriting the contents of UI_SHADER_HANDLE but come up against issues importing bevy_render::view. I'd also like to add custom parameters (i.e. border width), in a similar way that color and image are passed.

[ickshonpe]

You could look at #3991