Move `ListTileTheme` and its tests into separate classes and add...

Move `ListTileTheme` and its tests into separate classes and  add `visualDensity` to the `ListTileTheme` (#100622)

packages/flutter/lib/material.dart

@@ -94,6 +94,7 @@ export 'src/material/input_border.dart';
 export 'src/material/input_date_picker_form_field.dart';
 export 'src/material/input_decorator.dart';
 export 'src/material/list_tile.dart';
+export 'src/material/list_tile_theme.dart';
 export 'src/material/material.dart';
 export 'src/material/material_button.dart';
 export 'src/material/material_localizations.dart';

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

@@ -6,6 +6,7 @@ import 'package:flutter/widgets.dart';
 
 import 'checkbox.dart';
 import 'list_tile.dart';
+import 'list_tile_theme.dart';
 import 'theme.dart';
 import 'theme_data.dart';
 

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

@@ -9,6 +9,7 @@ import 'colors.dart';
 import 'debug.dart';
 import 'drawer_theme.dart';
 import 'list_tile.dart';
+import 'list_tile_theme.dart';
 import 'material.dart';
 import 'material_localizations.dart';
 import 'theme.dart';

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

@@ -9,6 +9,7 @@ import 'colors.dart';
 import 'expansion_tile_theme.dart';
 import 'icons.dart';
 import 'list_tile.dart';
+import 'list_tile_theme.dart';
 import 'theme.dart';
 
 const Duration _kExpand = Duration(milliseconds: 200);

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

@@ -5,6 +5,7 @@
 import 'package:flutter/widgets.dart';
 
 import 'list_tile.dart';
+import 'list_tile_theme.dart';
 import 'radio.dart';
 import 'theme.dart';
 import 'theme_data.dart';

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

@@ -5,6 +5,7 @@
 import 'package:flutter/widgets.dart';
 
 import 'list_tile.dart';
+import 'list_tile_theme.dart';
 import 'switch.dart';
 import 'theme.dart';
 import 'theme_data.dart';

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

@@ -31,6 +31,7 @@ import 'ink_splash.dart';
 import 'ink_well.dart' show InteractiveInkFeatureFactory;
 import 'input_decorator.dart';
 import 'list_tile.dart';
+import 'list_tile_theme.dart';
 import 'navigation_bar_theme.dart';
 import 'navigation_rail_theme.dart';
 import 'outlined_button_theme.dart';