MediaAccessibility tvOS xcode16.0 b4

#MediaAccessibility.framework https://github.com/xamarin/xamarin-macios/pull/21144

diff -ruN /Applications/Xcode_16.0.0-beta3.app/Contents/Developer/Platforms/AppleTVOS.platform/Developer/SDKs/AppleTVOS.sdk/System/Library/Frameworks/MediaAccessibility.framework/Headers/MACaptionAppearance.h /Applications/Xcode_16.0.0-beta4.app/Contents/Developer/Platforms/AppleTVOS.platform/Developer/SDKs/AppleTVOS.sdk/System/Library/Frameworks/MediaAccessibility.framework/Headers/MACaptionAppearance.h
--- /Applications/Xcode_16.0.0-beta3.app/Contents/Developer/Platforms/AppleTVOS.platform/Developer/SDKs/AppleTVOS.sdk/System/Library/Frameworks/MediaAccessibility.framework/Headers/MACaptionAppearance.h	2024-06-26 20:07:17
+++ /Applications/Xcode_16.0.0-beta4.app/Contents/Developer/Platforms/AppleTVOS.platform/Developer/SDKs/AppleTVOS.sdk/System/Library/Frameworks/MediaAccessibility.framework/Headers/MACaptionAppearance.h	2024-07-12 05:32:40
@@ -242,6 +242,16 @@
 MA_EXPORT
 CFArrayRef MACaptionAppearanceCopyPreferredCaptioningMediaCharacteristics(MACaptionAppearanceDomain domain) CF_AVAILABLE(10_9, 7_0);
 
+/*!
+ @function MACaptionAppearanceIsCustomized
+ @abstract Provides a boolean indicating if the currently-active style has been customized by the user. This is useful for some clients who may need different fallback strategies for customized styles vs system-default styles.
+ @param domain Preference domain, see  @link MACaptionAppearanceDomain @/link.
+ @result A boolean indicating if the currently-active style has been customized by the user
+ */
+MA_EXPORT
+bool MACaptionAppearanceIsCustomized(MACaptionAppearanceDomain domain) CF_AVAILABLE(15_0, 18_0);
+
+
 #pragma mark Color preferences
 /*——————————————————————————————————————————————————————————————————————————————————————*/
 /*! @group Color preferences                                                            */