iOS: Fixed the bug where a Backspace event was emitted when entering characters after clearing a text in TextInput by an empty string (#18627)

Summary:
The bug #18374 was caused by the loose condition to execute `stringByReplacingCharactersInRange` in the method `textInputShouldChangeTextInRange` . As a result, `findMismatch` wrongly returning `true` which ends up the Backspace event being fired in another `textInputShouldChangeTextInRange` call in `textInputDidChange`.

Closes facebook/react-native#18627

Differential Revision: D8436331

Pulled By: hramos

fbshipit-source-id: ec75a6ca926061cbf7cb106db652f2b4a71c9a0c

Author: hamaron

Libraries/Text/TextInput/RCTBaseTextInputView.m

@@ -278,7 +278,12 @@ - (BOOL)textInputShouldChangeTextInRange:(NSRange)range replacementText:(NSStrin
 
   NSString *previousText = [_predictedText substringWithRange:range] ?: @"";
 
-  if (_predictedText) {
+  // After clearing the text by replacing it with an empty string, `_predictedText`
+  // still preserves the deleted text.
+  // As the first character in the TextInput always comes with the range value (0, 0),
+  // we should check the range value in order to avoid appending a character to the deleted string
+  // (which caused the issue #18374)
+  if (!NSEqualRanges(range, NSMakeRange(0, 0)) && _predictedText) {
     _predictedText = [_predictedText stringByReplacingCharactersInRange:range withString:text];
   } else {
     _predictedText = [text copy];