Replaced RegExp method parser with recursive descent

Summary:
public

This diff replaces the RegEx module method parser with a handwritten recursive descent parser that's faster and easier to maintain.

The new parser is ~8 times faster when tested on the UIManager.managerChildren() method, and uses ~1/10 as much RAM.

The new parser also supports lightweight generics, and is more tolerant of white space.

(This means that you now can – and should – use types like `NSArray<NSString *> *` for your exported properties and method arguments, instead of `NSStringArray`).

Reviewed By: jspahrsummers

Differential Revision: D2736636

fb-gh-sync-id: f6a11431935fa8acc8ac36f3471032ec9a1c8490

React/Base/RCTModuleMethod.h

@@ -10,15 +10,10 @@
 #import <Foundation/Foundation.h>
 
 #import "RCTBridgeMethod.h"
+#import "RCTNullability.h"
 
 @class RCTBridge;
 
-typedef NS_ENUM(NSUInteger, RCTNullability) {
-  RCTNullabilityUnspecified,
-  RCTNullable,
-  RCTNonnullable,
-};
-
 @interface RCTMethodArgument : NSObject
 
 @property (nonatomic, copy, readonly) NSString *type;
@@ -32,7 +27,7 @@ typedef NS_ENUM(NSUInteger, RCTNullability) {
 @property (nonatomic, readonly) Class moduleClass;
 @property (nonatomic, readonly) SEL selector;
 
-- (instancetype)initWithObjCMethodName:(NSString *)objCMethodName
+- (instancetype)initWithMethodSignature:(NSString *)objCMethodName
                           JSMethodName:(NSString *)JSMethodName
                            moduleClass:(Class)moduleClass NS_DESIGNATED_INITIALIZER;