Make cancel button configurable in the AppBar (#139)

* added missing MultipleChoiceQuestionResult toJson

* Updated PlatformAppbar with default AppBar widget

* Updated IconButton -> BackButton

* Added other field in Multiple choice answers

* added Multiple choice autocomplete

* Customized the builder

* added comment

* DRY refactor

* Updated other field label behavior

* Added clear button and added tick mark check on dropdown

* Updated example

* Removed comment

* json file updated

* added default value for text question

* Boolean Answer defaultValue

* put back actual example_json.json

* Fixed consistent focus in non textfield views

There was a problem that keyboard was not hiding after navigating to
next question when the view is not text/double answer view

* added showCancelButton flag

* update build_runner dependency

* update flutter changes for android directory

* update flutter changes for ios directory

* update example pubspec.lock

* add missing JsonSerializable annotation for ImageQuestionResult

* re-run build_runner latest verson

* remove duplicate imports

Author: adar2378

lib/src/configuration/app_bar_configuration.dart

@@ -5,10 +5,12 @@ class AppBarConfiguration {
   final bool? canBack;
   final bool? showProgress;
   final Widget? trailing;
+  final bool? showCancelButton;
 
   const AppBarConfiguration({
     required this.canBack,
     required this.showProgress,
+    this.showCancelButton = true,
     this.leading,
     this.trailing,
   });

lib/src/views/widget/survey_app_bar.dart

@@ -34,18 +34,19 @@ class SurveyAppBar extends StatelessWidget {
           : Container(),
       title: _showProgress ? SurveyProgress() : SizedBox.shrink(),
       actions: [
-        TextButton(
-          child: appBarConfiguration.trailing ??
-              Text(
-                context.read<Map<String, String>?>()?['cancel'] ?? 'Cancel',
-                style: TextStyle(
-                  color: Theme.of(context).primaryColor,
+        if (appBarConfiguration.showCancelButton ?? true)
+          TextButton(
+            child: appBarConfiguration.trailing ??
+                Text(
+                  context.read<Map<String, String>?>()?['cancel'] ?? 'Cancel',
+                  style: TextStyle(
+                    color: Theme.of(context).primaryColor,
+                  ),
                 ),
-              ),
-          onPressed: () => surveyController.closeSurvey(
-            context: context,
+            onPressed: () => surveyController.closeSurvey(
+              context: context,
+            ),
           ),
-        ),
       ],
     );
   }