Import RCTTVRemoteHandler only on tvOS

Summary:
Fix issue #17027 (`RCTModalHostView` has a tvOS dependency that was not wrapped in `TARGET_OS_TV`)

Existing test automation should pass.

[GENERAL] [BUGFIX] [tvOS] Fix cocoapods compile issue in RCTModalHostView
Closes https://github.com/facebook/react-native/pull/17502

Differential Revision: D6688166

Pulled By: hramos

fbshipit-source-id: 38297f439f75a8303f59f83b92e004c6c73d9bf6

React/Views/RCTModalHostView.m

@@ -18,7 +18,9 @@
 #import "RCTUIManager.h"
 #import "RCTUtils.h"
 #import "UIView+React.h"
+#if TARGET_OS_TV
 #import "RCTTVRemoteHandler.h"
+#endif
 
 @implementation RCTModalHostView
 {