Stub for caretHidden prop in RCTUITextView

Summary:
Even if we don't support this prop yet, we have to expose this in RCTUITextView to conform the contract between ViewManager and ShadowView.
Same story as D6842304.
Depends on D6842304.

Reviewed By: fmoo

Differential Revision: D6869750

fbshipit-source-id: 9b35f1a38040319ec66f1ec12f97ac739f8b204f

Author: shergin

Libraries/Text/TextInput/Multiline/RCTUITextView.h

@@ -35,6 +35,10 @@ NS_ASSUME_NONNULL_BEGIN
 // it's declared here only to conform to the interface.
 @property (nonatomic, assign) UITextFieldViewMode clearButtonMode;
 
+// The `caretHidden` property actually is not supported yet;
+// it's declared here only to conform to the interface.
+@property (nonatomic, assign) BOOL caretHidden;
+
 @end
 
 NS_ASSUME_NONNULL_END