TextInput: Refactoring of RCTBackedTextInputViewProtocol (merging some props into defaultTextAttributes)

Summary:
Remove textColor font and textAlignment in RCTBackedTextInputViewProtocol since they're all wired up in defaultTextAttributes already

Changelog: [iOS] [Removed] Remove three properties:  "textColor" "font" "textAlignment" from RCTBackedTextInputViewProtocol, unifying the usage into "defaultTextAttributes".

Reviewed By: PeteTheHeat

Differential Revision: D18954292

fbshipit-source-id: 17fd38a824d035843ae59b1b875dd9c48b3fcc9b

Author: jimmy623

Libraries/Text/TextInput/RCTBackedTextInputViewProtocol.h

@@ -14,12 +14,9 @@ NS_ASSUME_NONNULL_BEGIN
 
 @protocol RCTBackedTextInputViewProtocol <UITextInput>
 
-@property (nonatomic, strong, nullable) UIColor *textColor; // TODO: T57162853 Merge with `defaultTextAttributes`.
-@property (nonatomic, strong, nullable) UIFont *font; // TODO: T57162853 Merge with `defaultTextAttributes`.
 @property (nonatomic, copy, nullable) NSAttributedString *attributedText;
 @property (nonatomic, copy, nullable) NSString *placeholder;
 @property (nonatomic, strong, nullable) UIColor *placeholderColor;
-@property (nonatomic, assign) NSTextAlignment textAlignment; // TODO: T57162853 Merge with `defaultTextAttributes`.
 @property (nonatomic, assign, readonly) BOOL textWasPasted;
 @property (nonatomic, assign) UIEdgeInsets textContainerInset;
 @property (nonatomic, strong, nullable) UIView *inputAccessoryView;