Update Tab semantics in Cupertino to be the same as Material (#56582)

packages/flutter/lib/src/cupertino/localizations.dart

@@ -262,7 +262,7 @@ class _CupertinoLocalizationsDelegate extends LocalizationsDelegate<CupertinoLoc
   String toString() => 'DefaultCupertinoLocalizations.delegate(en_US)';
 }
 
-/// US English strings for the cupertino widgets.
+/// US English strings for the Cupertino widgets.
 class DefaultCupertinoLocalizations implements CupertinoLocalizations {
   /// Constructs an object that defines the cupertino widgets' localized strings
   /// for US English (only).
@@ -367,7 +367,7 @@ class DefaultCupertinoLocalizations implements CupertinoLocalizations {
   String tabSemanticsLabel({int tabIndex, int tabCount}) {
     assert(tabIndex >= 1);
     assert(tabCount >= 1);
-    return 'tab, $tabIndex of $tabCount';
+    return 'Tab $tabIndex of $tabCount';
   }
 
   @override

packages/flutter/test/cupertino/bottom_tab_bar_test.dart

@@ -385,14 +385,14 @@ void main() {
 
     expect(semantics, includesNodeWith(
       label: 'Tab 1',
-      hint: 'tab, 1 of 2',
+      hint: 'Tab 1 of 2',
       flags: <SemanticsFlag>[SemanticsFlag.isSelected],
       textDirection: TextDirection.ltr,
     ));
 
     expect(semantics, includesNodeWith(
       label: 'Tab 2',
-      hint: 'tab, 2 of 2',
+      hint: 'Tab 2 of 2',
       textDirection: TextDirection.ltr,
     ));
 

packages/flutter_localizations/lib/src/l10n/cupertino_en.arb

@@ -43,7 +43,7 @@
     "description": "The accessibility audio announcement made when an iOS style alert dialog is opened."
   },
 
-  "tabSemanticsLabel": "tab, $tabIndex of $tabCount",
+  "tabSemanticsLabel": "Tab $tabIndex of $tabCount",
   "@tabSemanticsLabel": {
     "description": "The accessibility label used on a tab. This message describes the index of the selected tab and how many tabs there are, e.g. 'tab, 1 of 2'. All values are greater than or equal to one.",
     "parameters": "tabIndex, tabCount"

packages/flutter_localizations/lib/src/l10n/generated_cupertino_localizations.dart

@@ -2271,7 +2271,7 @@ class CupertinoLocalizationEn extends GlobalCupertinoLocalizations {
   String get selectAllButtonLabel => 'Select All';
 
   @override
-  String get tabSemanticsLabelRaw => 'tab, \$tabIndex of \$tabCount';
+  String get tabSemanticsLabelRaw => 'Tab \$tabIndex of \$tabCount';
 
   @override
   String get timerPickerHourLabelFew => null;