Replace deprecated onBackPressed with onBackPressedDispatcher (#3389)

Replaced deprecated `onBackPressed` with `onBackPressedDispatcher`. The `onBackPressedDispatcher` handles the home button press by delegating to the appropriate back navigation method.

V2rayNG/app/src/main/kotlin/com/v2ray/ang/ui/BaseActivity.kt

@@ -23,7 +23,9 @@ abstract class BaseActivity : AppCompatActivity() {
 
     override fun onOptionsItemSelected(item: MenuItem) = when (item.itemId) {
         android.R.id.home -> {
-            onBackPressed()
+            // Handles the home button press by delegating to the onBackPressedDispatcher.
+            // This ensures consistent back navigation behavior.
+            onBackPressedDispatcher.onBackPressed()
             true
         }
         else -> super.onOptionsItemSelected(item)