fix(Android, Stack v5): fix lifecycle of prevent native dismiss callback (#3635)

## Description

There is no memory leak currently, because PreventNativeDismissCallback
does not retain the fragment (lifecycleOwner), it registers itself as a
listener on it, so it's the fragment who retains it x2 (explicitly & in
listener array). The callback unregisters when fragment is destroyed.

The problem is however, that the callback registers as a listener in its
init block, effectively doing it once per object lifetime, even if the
fragment is reattached to the fragment manager the callback won't
initialize again effectively breaking the prevent-native-dismiss
behavior.

## Changes

I fix this by setting up the callback in onCreate & destroying it in
onDestroy.

## Visual documentation

N/A

## Checklist

- [x] Ensured that CI passes

Author: kkafar

android/src/main/java/com/swmansion/rnscreens/gamma/stack/screen/StackScreenFragment.kt

@@ -18,16 +18,15 @@ internal class StackScreenFragment(
      * Since each StackScreenFragment owns a PreventNativeDismissCallback & adds it to the
      * OnBackPressedDispatcher the callback should be enabled only when the top fragment is this fragment.
      */
-    private val preventNativeDismissBackPressedCallback =
-        PreventNativeDismissCallback(this, stackScreen, canBeEnabled = true)
+    private var preventNativeDismissBackPressedCallback: PreventNativeDismissCallback? = null
+    private val requireNativeDismissBackPressedCallback
+        get() = checkNotNull(preventNativeDismissBackPressedCallback) { "[RNScreens] Attempt to require nullish OnBackPressedCallback" }
 
     private var isTopFragment: Boolean = false
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
-        requireActivity().onBackPressedDispatcher.addCallback(
-            preventNativeDismissBackPressedCallback,
-        )
+        setupPreventNativeDismissCallback()
     }
 
     override fun onCreateView(
@@ -53,30 +52,45 @@ internal class StackScreenFragment(
         super.onDestroy()
         Log.i("StackScreenFragment", "onDestroy")
         stackScreen.onDismiss()
-        preventNativeDismissBackPressedCallback.remove()
+        teardownPreventNativeDismissCallback()
     }
 
     /**
      * Notifies this fragment that it has become "top fragment" in its fragment manager.
+     * Call this only if the lifecycle of the fragment is at least at CREATED.
      *
      * This function should be idempotent.
      */
     internal fun onBecomeTopFragment() {
         if (isTopFragment) return
 
         isTopFragment = true
-        preventNativeDismissBackPressedCallback.canBeEnabled = true
+        requireNativeDismissBackPressedCallback.canBeEnabled = true
     }
 
     /**
      * Notifies this fragment that it is not longer the "top fragment" in its fragment manager.
+     * Call this only if the lifecycle of the fragment is at least at CREATED.
      *
      * This function should be idempotent.
      */
     internal fun onResignTopFragment() {
         if (!isTopFragment) return
 
         isTopFragment = false
-        preventNativeDismissBackPressedCallback.canBeEnabled = false
+        requireNativeDismissBackPressedCallback.canBeEnabled = false
+    }
+
+    private fun setupPreventNativeDismissCallback() {
+        preventNativeDismissBackPressedCallback =
+            PreventNativeDismissCallback(this, stackScreen, canBeEnabled = false)
+        requireActivity().onBackPressedDispatcher.addCallback(
+            requireNativeDismissBackPressedCallback,
+        )
+    }
+
+    private fun teardownPreventNativeDismissCallback() {
+        requireNativeDismissBackPressedCallback.remove()
+        preventNativeDismissBackPressedCallback = null
     }
 }