Do not send extra onChangeText even wnen instantianting multiline TextView (#36930)

Summary:
Pull Request resolved: #36930

This diff fixes #36494

Now this code matches its [Fabric counterpart](7b48899).

There is also one extra check that `_lastStringStateWasUpdatedWith != nil`. With that in place we don't send extra `onChangeText` event when `attributedText` is assigned for the first time on TextView construction.

Changelog: [IOS][Fixed] - Do not send extra onChangeText even wnen instantianting multiline TextView

Reviewed By: sammy-SC

Differential Revision: D45049135

fbshipit-source-id: 3351b9b62fca5e8722c8da08f2c081b857164458

Author: dmytrorykun

packages/react-native/Libraries/Text/TextInput/RCTBackedTextInputDelegateAdapter.m

@@ -256,21 +256,21 @@ - (BOOL)textView:(__unused UITextView *)textView shouldChangeTextInRange:(NSRang
 
 - (void)textViewDidChange:(__unused UITextView *)textView
 {
-  if (_ignoreNextTextInputCall && [_lastStringStateWasUpdatedWith isEqual:_backedTextInputView.attributedText]) {
+  if (_ignoreNextTextInputCall) {
     _ignoreNextTextInputCall = NO;
     return;
   }
-  _lastStringStateWasUpdatedWith = _backedTextInputView.attributedText;
   _textDidChangeIsComing = NO;
   [_backedTextInputView.textInputDelegate textInputDidChange];
 }
 
 - (void)textViewDidChangeSelection:(__unused UITextView *)textView
 {
-  if (![_lastStringStateWasUpdatedWith isEqual:_backedTextInputView.attributedText]) {
+  if (_lastStringStateWasUpdatedWith && ![_lastStringStateWasUpdatedWith isEqual:_backedTextInputView.attributedText]) {
     [self textViewDidChange:_backedTextInputView];
     _ignoreNextTextInputCall = YES;
   }
+  _lastStringStateWasUpdatedWith = _backedTextInputView.attributedText;
   [self textViewProbablyDidChangeSelection];
 }