Update the example + Few more changes

Author: EchoEllet

lib/flutter_quill.dart

@@ -17,7 +17,6 @@ export 'src/models/structs/link_dialog_action.dart';
 export 'src/models/structs/offset_value.dart';
 export 'src/models/structs/optional_size.dart';
 export 'src/models/structs/vertical_spacing.dart';
-export 'src/models/themes/quill_custom_button.dart';
 export 'src/models/themes/quill_dialog_theme.dart';
 export 'src/models/themes/quill_icon_theme.dart';
 export 'src/utils/embeds.dart';

lib/src/widgets/toolbar/buttons/custom_button.dart

@@ -1,6 +1,5 @@
 import 'package:flutter/material.dart';
 
-import '../../../models/config/toolbar/buttons/custom_button.dart';
 import '../../../models/themes/quill_icon_theme.dart';
 import '../../../utils/extensions/build_context.dart';
 import '../../controller.dart';

test/bug_fix_test.dart

@@ -1,6 +1,5 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_quill/flutter_quill.dart';
-import 'package:flutter_quill/src/models/config/toolbar/buttons/custom_button.dart';
 import 'package:flutter_quill_test/flutter_quill_test.dart';
 import 'package:flutter_test/flutter_test.dart';