Use material translations for common words

lib/helpers/ui.dart

@@ -34,7 +34,7 @@ void showErrorDialog(dynamic exception, BuildContext context) {
       content: Text(exception.toString()),
       actions: [
         TextButton(
-          child: Text(AppLocalizations.of(context)!.dismiss),
+          child: Text(MaterialLocalizations.of(context).closeButtonLabel),
           onPressed: () {
             Navigator.of(ctx).pop();
           },
@@ -76,7 +76,7 @@ void showHttpExceptionErrorDialog(WgerHttpException exception, BuildContext cont
       ),
       actions: [
         TextButton(
-          child: Text(AppLocalizations.of(context)!.dismiss),
+          child: Text(MaterialLocalizations.of(context).closeButtonLabel),
           onPressed: () {
             Navigator.of(ctx).pop();
           },

lib/l10n/app_en.arb

@@ -188,8 +188,6 @@
   "@description": {},
   "save": "Save",
   "@save": {},
-  "cancel": "Cancel",
-  "@cancel": {},
   "addSet": "Add set",
   "@addSet": {
     "description": "Label for the button that adds a set (to a workout day)"
@@ -214,8 +212,6 @@
   },
   "anErrorOccurred": "An Error Occurred!",
   "@anErrorOccurred": {},
-  "dismiss": "Dismiss",
-  "@dismiss": {},
   "weight": "Weight",
   "@weight": {
     "description": "The weight of a workout log or body weight entry"

lib/widgets/nutrition/nutritional_plans_list.dart

@@ -46,7 +46,7 @@ class NutritionalPlansList extends StatelessWidget {
                     ),
                     actions: [
                       TextButton(
-                        child: Text(AppLocalizations.of(context)!.cancel),
+                        child: Text(MaterialLocalizations.of(context).cancelButtonLabel),
                         onPressed: () => Navigator.of(contextDialog).pop(),
                       ),
                       TextButton(

lib/widgets/workouts/day.dart

@@ -61,7 +61,7 @@ class SettingWidget extends StatelessWidget {
                 content: ExerciseDetail(setting.exerciseObj),
                 actions: [
                   TextButton(
-                    child: Text(AppLocalizations.of(context)!.dismiss),
+                    child: Text(MaterialLocalizations.of(context).closeButtonLabel),
                     onPressed: () {
                       Navigator.of(context).pop();
                     },

lib/widgets/workouts/workout_plans_list.dart

@@ -48,7 +48,7 @@ class WorkoutPlansList extends StatelessWidget {
                     ),
                     actions: [
                       TextButton(
-                        child: Text(AppLocalizations.of(context)!.cancel),
+                        child: Text(MaterialLocalizations.of(context).cancelButtonLabel),
                         onPressed: () => Navigator.of(contextDialog).pop(),
                       ),
                       TextButton(