Fix #134260: Color Picker components partially resetting when pressing Backspace

Previously, when pressing the Backspace key inside an open color picker,
the HSV and Hex field components would not refresh. Only the RGB
components would.

Fixed by calling the attached button function callbacks which propagates
the color changes to the other color picker buttons from the RGB values.

Pull Request: https://projects.blender.org/blender/blender/pulls/135131

source/blender/editors/interface/interface_handlers.cc

@@ -6940,6 +6940,7 @@ static int ui_do_but_HSVCUBE(
 
           ui_color_picker_to_rgb_HSVCUBE_v(hsv_but, def_hsv, rgb);
           ui_but_v3_set(but, rgb);
+          ui_apply_but_func(C, but);
 
           RNA_property_update(C, &but->rnapoin, but->rnaprop);
           return WM_UI_HANDLER_BREAK;
@@ -7210,6 +7211,7 @@ static int ui_do_but_HSVCIRCLE(
 
         hsv_to_rgb_v(def_hsv, rgb);
         ui_but_v3_set(but, rgb);
+        ui_apply_but_func(C, but);
 
         RNA_property_update(C, &but->rnapoin, but->rnaprop);