Add a property hint to StyleBoxFlat `shadow_size` for editor usability

This adds a visible range to the slider so it can be dragged more easily.

This closes #42309.

scene/resources/style_box.cpp

@@ -911,7 +911,7 @@ void StyleBoxFlat::_bind_methods() {
 
 	ADD_GROUP("Shadow", "shadow_");
 	ADD_PROPERTY(PropertyInfo(Variant::COLOR, "shadow_color"), "set_shadow_color", "get_shadow_color");
-	ADD_PROPERTY(PropertyInfo(Variant::INT, "shadow_size"), "set_shadow_size", "get_shadow_size");
+	ADD_PROPERTY(PropertyInfo(Variant::INT, "shadow_size", PROPERTY_HINT_RANGE, "0,100,1,or_greater"), "set_shadow_size", "get_shadow_size");
 	ADD_PROPERTY(PropertyInfo(Variant::VECTOR2, "shadow_offset"), "set_shadow_offset", "get_shadow_offset");
 
 	ADD_GROUP("Anti Aliasing", "anti_aliasing_");