Swap order of shortcut map merging so that customShortcuts are added first and override existing duplicate trigger shortcuts by absorbing the input first (#2089)

Co-authored-by: ryanscott0515 <ryanscott0515@gmail.com>

lib/src/editor/raw_editor/raw_editor_state.dart

@@ -533,7 +533,12 @@ class QuillRawEditorState extends EditorState
       child: QuillStyles(
         data: _styles!,
         child: Shortcuts(
-          shortcuts: mergeMaps<ShortcutActivator, Intent>({
+          /// Merge with widget.configurations.customShortcuts
+          /// first to allow user's defined shortcuts to take
+          /// priority when activation triggers are the same
+          shortcuts: mergeMaps<ShortcutActivator, Intent>(
+            {...?widget.configurations.customShortcuts},
+            {
               // shortcuts added for Desktop platforms.
               const SingleActivator(
                 LogicalKeyboardKey.escape,
@@ -710,10 +715,10 @@ class QuillRawEditorState extends EditorState
                 control: !isDesktopMacOS,
                 meta: isDesktopMacOS,
               ): const ScrollIntent(
-                direction: AxisDirection.down, type: ScrollIncrementType.page),
-          }, {
-            ...?widget.configurations.customShortcuts
-          }),
+                  direction: AxisDirection.down,
+                  type: ScrollIncrementType.page),
+            },
+          ),
           child: Actions(
             actions: mergeMaps<Type, Action<Intent>>(_actions, {
               ...?widget.configurations.customActions,