Bring back the UNSET constant to TextAttributeProps (#43491)

Summary:
Pull Request resolved: #43491

This diff brings back the `UNSET` constant to `TextAttributeProps`.
The removal of this constant was an unnecessary breaking change, that has broken several third-party libraries.

Changelog: [Android][Fixed] - Bring back the UNSET constant to TextAttributeProps.

Reviewed By: fabriziocucci

Differential Revision: D54899524

fbshipit-source-id: 368bde77d43f310fd458537d0191d09174fa5167

Author: dmytrorykun

packages/react-native/ReactAndroid/api/ReactAndroid.api

@@ -7083,6 +7083,7 @@ public class com/facebook/react/views/text/TextAttributeProps : com/facebook/rea
 	public static final field TA_KEY_TEXT_SHADOW_OFFSET_DY S
 	public static final field TA_KEY_TEXT_SHADOW_RADIUS S
 	public static final field TA_KEY_TEXT_TRANSFORM S
+	public static final field UNSET I
 	protected field mAccessibilityRole Lcom/facebook/react/uimanager/ReactAccessibilityDelegate$AccessibilityRole;
 	protected field mAllowFontScaling Z
 	protected field mBackgroundColor I

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/views/text/TextAttributeProps.java

@@ -62,6 +62,8 @@ public class TextAttributeProps implements EffectiveTextAttributeProvider {
   public static final short TA_KEY_ROLE = 26;
   public static final short TA_KEY_TEXT_TRANSFORM = 27;
 
+  public static final int UNSET = -1;
+
   private static final String PROP_SHADOW_OFFSET = "textShadowOffset";
   private static final String PROP_SHADOW_OFFSET_WIDTH = "width";
   private static final String PROP_SHADOW_OFFSET_HEIGHT = "height";