Save current page state on configuration change

Fixes #8881

The actual issue is that the ViewModel migration actually differs between what the current `init` block
and previous `onSave` methods did; where the `init` block does not get triggered on saving the
instance on config changes.

Not entirely sure why onSaveInstanceState was explicitly avoided for config changes before, but we
just do it all the time now and end up updating the requestedPage with the current page.

app/src/main/java/eu/kanade/tachiyomi/ui/reader/ReaderActivity.kt

@@ -269,9 +269,7 @@ class ReaderActivity : BaseActivity() {
      */
     override fun onSaveInstanceState(outState: Bundle) {
         outState.putBoolean(::menuVisible.name, menuVisible)
-        if (!isChangingConfigurations) {
-            viewModel.onSaveInstanceStateNonConfigurationChange()
-        }
+        viewModel.onSaveInstanceState()
         super.onSaveInstanceState(outState)
     }
 

app/src/main/java/eu/kanade/tachiyomi/ui/reader/ReaderViewModel.kt

@@ -232,10 +232,10 @@ class ReaderViewModel(
     }
 
     /**
-     * Called when the activity is saved and not changing configurations. It updates the database
+     * Called when the activity is saved. It updates the database
      * to persist the current progress of the active chapter.
      */
-    fun onSaveInstanceStateNonConfigurationChange() {
+    fun onSaveInstanceState() {
         val currentChapter = getCurrentChapter() ?: return
         viewModelScope.launchNonCancellable {
             saveChapterProgress(currentChapter)
@@ -512,6 +512,7 @@ class ReaderViewModel(
     private suspend fun saveChapterProgress(readerChapter: ReaderChapter) {
         if (!incognitoMode || hasTrackers) {
             val chapter = readerChapter.chapter
+            getCurrentChapter()?.requestedPage = chapter.last_page_read
             updateChapter.await(
                 ChapterUpdate(
                     id = chapter.id!!,