[macOS] Add explicit weak/strong/copy annotations (#37768)

This adds explicit strong/copy Objective-C property annotations where
they were previously implied on NSObject properties and fixes on case
where it was previously improperly specified.

Author: cbracken

shell/platform/darwin/macos/framework/Headers/FlutterDartProject.h

@@ -44,7 +44,7 @@ FLUTTER_DARWIN_EXPORT
  *
  * Set this to nil to pass no arguments to the Dart entrypoint.
  */
-@property(nonatomic, nullable, strong) NSArray<NSString*>* dartEntrypointArguments;
+@property(nonatomic, nullable, copy) NSArray<NSString*>* dartEntrypointArguments;
 
 @end
 

shell/platform/darwin/macos/framework/Headers/FlutterViewController.h

@@ -115,6 +115,6 @@ FLUTTER_DARWIN_EXPORT
  * }
  * ```
  */
-@property(readwrite, nonatomic, nullable) NSColor* backgroundColor;
+@property(readwrite, nonatomic, nullable, copy) NSColor* backgroundColor;
 
 @end

shell/platform/darwin/macos/framework/Source/FlutterEmbedderKeyResponder.mm

@@ -285,7 +285,7 @@ - (void)resolveTo:(BOOL)handled;
  * Only set in debug mode. Nil in release mode, or if the callback has not been
  * handled.
  */
-@property(nonatomic) NSString* debugHandleSource;
+@property(nonatomic, copy) NSString* debugHandleSource;
 @end
 
 @implementation FlutterKeyCallbackGuard {

shell/platform/darwin/macos/framework/Source/FlutterKeyPrimaryResponder.h

@@ -31,6 +31,6 @@ typedef void (^FlutterAsyncKeyCallback)(BOOL handled);
  * deriving logical keys.
  */
 @required
-@property(nonatomic) NSMutableDictionary<NSNumber*, NSNumber*>* _Nullable layoutMap;
+@property(nonatomic, nullable, strong) NSMutableDictionary<NSNumber*, NSNumber*>* layoutMap;
 
 @end

shell/platform/darwin/macos/framework/Source/FlutterKeyboardManagerTest.mm

@@ -211,8 +211,8 @@ - (void)respondTextInputWith:(BOOL)response;
 - (void)recordCallTypesTo:(nonnull NSMutableArray<NSNumber*>*)typeStorage
                  forTypes:(uint32_t)typeMask;
 
-@property(nonatomic) FlutterKeyboardManager* manager;
-@property(nonatomic) NSResponder* nextResponder;
+@property(readonly, nonatomic, strong) FlutterKeyboardManager* manager;
+@property(nonatomic, nullable, strong) NSResponder* nextResponder;
 
 #pragma mark - Private
 

shell/platform/darwin/macos/framework/Source/FlutterTextInputPluginTest.mm

@@ -18,7 +18,7 @@ - (void)setPlatformNode:(flutter::FlutterTextPlatformNode*)node;
 
 @interface FlutterTextFieldMock : FlutterTextField
 
-@property(nonatomic) NSString* lastUpdatedString;
+@property(nonatomic, nullable, copy) NSString* lastUpdatedString;
 @property(nonatomic) NSRange lastUpdatedSelection;
 
 @end