fix: prevent activity recreation on theme change (#26413)

Summary:
On Android 10 whole activity is recreated when the user changes system theme. We should prevent it by adding `uiMode` in `android:configChanges` key in the default template.

## Changelog

[Android] [Fixed] - Android 10: Prevent activity recreation on theme change
Pull Request resolved: #26413

Test Plan: NOOP

Differential Revision: D17342811

Pulled By: cpojer

fbshipit-source-id: 2bed9b5f91e1b67451fefe34b02a1129d6c80d15

template/android/app/src/main/AndroidManifest.xml

@@ -13,7 +13,7 @@
       <activity
         android:name=".MainActivity"
         android:label="@string/app_name"
-        android:configChanges="keyboard|keyboardHidden|orientation|screenSize"
+        android:configChanges="keyboard|keyboardHidden|orientation|screenSize|uiMode"
         android:windowSoftInputMode="adjustResize">
         <intent-filter>
             <action android:name="android.intent.action.MAIN" />