feat: Add cursorHeight to DropdownMenu (#172615)

This change adds the `cursorHeight` property to `DropdownMenu`, allowing
developers to customize the cursor height in the text field within the
dropdown.

The `cursorHeight` property is passed down to the underlying `TextField`
widget.

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fixes #172425 

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- [x] I updated/added relevant documentation (doc comments with `///`).
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---------

Co-authored-by: Qun Cheng <36861262+QuncCccccc@users.noreply.github.com>

packages/flutter/lib/src/material/dropdown_menu.dart

@@ -194,6 +194,7 @@ class DropdownMenu<T> extends StatefulWidget {
     this.closeBehavior = DropdownMenuCloseBehavior.all,
     this.maxLines = 1,
     this.textInputAction,
+    this.cursorHeight,
     this.restorationId,
   }) : assert(filterCallback == null || enableFilter),
        assert(
@@ -558,6 +559,9 @@ class DropdownMenu<T> extends StatefulWidget {
   /// {@macro flutter.widgets.TextField.textInputAction}
   final TextInputAction? textInputAction;
 
+  /// {@macro flutter.widgets.editableText.cursorHeight}
+  final double? cursorHeight;
+
   /// {@macro flutter.material.textfield.restorationId}
   final String? restorationId;
 
@@ -1112,6 +1116,7 @@ class _DropdownMenuState<T> extends State<DropdownMenu<T>> {
           textAlignVertical: TextAlignVertical.center,
           maxLines: widget.maxLines,
           textInputAction: widget.textInputAction,
+          cursorHeight: widget.cursorHeight,
           style: effectiveTextStyle,
           controller: _effectiveTextEditingController,
           onEditingComplete: _handleEditingComplete,

packages/flutter/test/material/dropdown_menu_test.dart

@@ -4515,6 +4515,23 @@ void main() {
       expect(selectedValueText.style.color, disabledColor);
     },
   );
+
+  testWidgets('DropdownMenu can set cursorHeight', (WidgetTester tester) async {
+    const double cursorHeight = 4.0;
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Scaffold(
+          body: DropdownMenu<TestMenu>(
+            cursorHeight: cursorHeight,
+            dropdownMenuEntries: menuChildren,
+          ),
+        ),
+      ),
+    );
+
+    final EditableText editableText = tester.widget(find.byType(EditableText));
+    expect(editableText.cursorHeight, cursorHeight);
+  });
 }
 
 enum TestMenu {