Add `axis` parameter to `SelectHeaderStyleButton`

lib/src/widgets/toolbar.dart

@@ -376,6 +376,7 @@ class QuillToolbar extends StatelessWidget implements PreferredSizeWidget {
         if (showHeaderStyle)
           SelectHeaderStyleButton(
             controller: controller,
+            axis: axis,
             iconSize: toolbarIconSize,
             iconTheme: iconTheme,
             afterButtonPressed: afterButtonPressed,

lib/src/widgets/toolbar/select_header_style_button.dart

@@ -10,6 +10,7 @@ import '../toolbar.dart';
 class SelectHeaderStyleButton extends StatefulWidget {
   const SelectHeaderStyleButton({
     required this.controller,
+    this.axis = Axis.horizontal,
     this.iconSize = kDefaultIconSize,
     this.iconTheme,
     this.attributes = const [
@@ -23,6 +24,7 @@ class SelectHeaderStyleButton extends StatefulWidget {
   }) : super(key: key);
 
   final QuillController controller;
+  final Axis axis;
   final double iconSize;
   final QuillIconTheme? iconTheme;
   final List<Attribute> attributes;
@@ -67,9 +69,7 @@ class _SelectHeaderStyleButtonState extends State<SelectHeaderStyleButton> {
       fontSize: widget.iconSize * 0.7,
     );
 
-    return Row(
-      mainAxisSize: MainAxisSize.min,
-      children: widget.attributes.map((attribute) {
+    final children =  widget.attributes.map((attribute) {
       final isSelected = _selectedAttribute == attribute;
       return Padding(
         // ignore: prefer_const_constructors
@@ -112,7 +112,16 @@ class _SelectHeaderStyleButtonState extends State<SelectHeaderStyleButton> {
           ),
         ),
       );
-      }).toList(),
+    }).toList();
+
+    return widget.axis == Axis.horizontal
+        ? Row(
+            mainAxisSize: MainAxisSize.min,
+            children: children,
+          )
+        : Column(
+            mainAxisSize: MainAxisSize.min,
+            children: children,
           );
   }