feat: add the strokeWidthOnChanged callback.

[yfming93]

feat: add the strokeWidthOnChanged callback. A callback function that will be called when the stroke width on changed. It is convenient without having to set different stroke width every time you in painting. Different widths for different people. Set once ,used the last width at any time.

paintEditorConfigs : PaintEditorConfigs(
   initialStrokeWidth: myLocalizedStorageWidth,
   strokeWidthOnChanged: (x){
     myLocalizedStorageWidth = x;
   }
 ),

[yfming93]

I had reviewed.

[MarcioPereira155]

I have an infinite loop after finishing the edited image, the message Changes are being applied appears, and it does not return to the previous page, does anyone know why?