Fixed placeholder font not consistent with text's font when in multiline mode (#23654)

Summary:
Placeholder's font not consistent with text's font, it leads to cursor dislocation. We need to keep consistent between placeholder and text.

[iOS] [Fixed] - Fixed placeholder font not consistent with text's font when in multiline mode
Pull Request resolved: https://github.com/facebook/react-native/pull/23654

Differential Revision: D14226174

Pulled By: hramos

fbshipit-source-id: 7cfb3b73d8799d22d5cbbfe557df8de3f5fcf034

Libraries/Text/TextInput/Multiline/RCTUITextView.m

@@ -98,6 +98,7 @@ static UIColor *defaultPlaceholderColor()
   }
   self.typingAttributes = reactTextAttributes.effectiveTextAttributes;
   _reactTextAttributes = reactTextAttributes;
+  _placeholderView.font = self.font ?: defaultPlaceholderFont();
 }
 
 - (RCTTextAttributes *)reactTextAttributes