feat(iOS): added lineBreakStrategy attribute to Text/TextInput (#31272)

Summary:
iOS did not support the implementation of Korean word-wrap(line-break) before iOS14.
If the attribute applied, the word-wrap of Korean will works.

## Changelog

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[iOS] [Added] -  Line break strategy for Text and TextInput components

Pull Request resolved: https://github.com/facebook/react-native/pull/31272

Test Plan:
1. Test build and run on above iOS 14.
2. Test it does not affect existing text components when set default(none) strategy.
3. Test whether word-wrap works with Korean when set hangul-word strategy.

<img src="https://user-images.githubusercontent.com/26326015/112963967-d7f70c00-9182-11eb-9a34-8c758b80c219.png" width="300" height="" style="max-width:100%;">

Reviewed By: javache

Differential Revision: D39824809

Pulled By: lunaleaps

fbshipit-source-id: 42cb0385221a38c84e80d3494d1bfc1934ecf32b

React/Base/RCTConvert.h

@@ -65,6 +65,7 @@ typedef NSURL RCTFileURL;
 + (NSTextAlignment)NSTextAlignment:(id)json;
 + (NSUnderlineStyle)NSUnderlineStyle:(id)json;
 + (NSWritingDirection)NSWritingDirection:(id)json;
++ (NSLineBreakStrategy)NSLineBreakStrategy:(id)json;
 + (UITextAutocapitalizationType)UITextAutocapitalizationType:(id)json;
 + (UITextFieldViewMode)UITextFieldViewMode:(id)json;
 + (UIKeyboardType)UIKeyboardType:(id)json;

React/Base/RCTConvert.m

@@ -375,6 +375,25 @@ RCT_ENUM_CONVERTER(
     NSWritingDirectionNatural,
     integerValue)
 
++ (NSLineBreakStrategy)NSLineBreakStrategy:(id)json RCT_DYNAMIC
+{
+  if (@available(iOS 14.0, *)) {
+    static NSDictionary *mapping;
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+      mapping = @{
+        @"none" : @(NSLineBreakStrategyNone),
+        @"standard" : @(NSLineBreakStrategyStandard),
+        @"hangul-word" : @(NSLineBreakStrategyHangulWordPriority),
+        @"push-out" : @(NSLineBreakStrategyPushOut)
+      };
+    });
+    return RCTConvertEnumValue("NSLineBreakStrategy", mapping, @(NSLineBreakStrategyNone), json).integerValue;
+  } else {
+    return NSLineBreakStrategyNone;
+  }
+}
+
 RCT_ENUM_CONVERTER(
     UITextAutocapitalizationType,
     (@{