ThemeChangeAwareActivity: recreate activity after changing theme

API 21 had issues without this.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

ui/src/main/java/com/wireguard/android/activity/ThemeChangeAwareActivity.java

@@ -42,6 +42,7 @@ public abstract class ThemeChangeAwareActivity extends AppCompatActivity impleme
                     sharedPreferences.getBoolean(key, false) ?
                             AppCompatDelegate.MODE_NIGHT_YES :
                             AppCompatDelegate.MODE_NIGHT_NO);
+            recreate();
         }
     }
 }