iOS: Fix autoCorrect doesn't revert to initial state

Summary:
There's an inconsistency in autoCorrect's default state:
  - If you don't specify a value for autoCorrect, it defaults to on.
  - If you specify true/false for autoCorrect and later specify null, autoCorrect turns off. It should have reverted to its initial state of on.

The reason for this discrepancy is that autoCorrect is exposed to JS as a boolean but it is actually an enum with three states in native:
  - UITextAutocorrectionTypeDefault (the default value)
  - UITextAutocorrectionTypeYes
  - UITextAutocorrectionTypeNo

This is fixed by explicitly mapping JS null to UITextAutocorrectionTypeDefault.

**Test plan (required)**

Verified that switching `autoCorrect` between `true`, `false`, and `null` all work correctly in single line and multiline `TextInputs`.

Adam Comella
Microsoft Corp.
Closes https://github.com/facebook/react-native/pull/11055

Differential Revision: D4226419

Pulled By: javache

fbshipit-source-id: e3e5769a3aa537f00fb56ca4ae622ff4213481c5

Libraries/Text/RCTTextFieldManager.m

@@ -13,6 +13,7 @@
 #import "RCTShadowView.h"
 #import "RCTTextField.h"
 #import "RCTFont.h"
+#import "RCTConvert+Text.h"
 
 @interface RCTTextFieldManager() <UITextFieldDelegate>
 
@@ -75,7 +76,7 @@ RCT_EXPORT_MODULE()
 }
 
 RCT_EXPORT_VIEW_PROPERTY(caretHidden, BOOL)
-RCT_EXPORT_VIEW_PROPERTY(autoCorrect, BOOL)
+RCT_REMAP_VIEW_PROPERTY(autoCorrect, autocorrectionType, UITextAutocorrectionType)
 RCT_REMAP_VIEW_PROPERTY(editable, enabled, BOOL)
 RCT_EXPORT_VIEW_PROPERTY(placeholder, NSString)
 RCT_EXPORT_VIEW_PROPERTY(placeholderTextColor, UIColor)