add a "Temporarily show hidden" menu button to media view

app/src/main/kotlin/com/simplemobiletools/gallery/activities/MediaActivity.kt

@@ -88,6 +88,11 @@ class MediaActivity : SimpleActivity(), MediaAdapter.MediaOperationsListener {
         MyScalableRecyclerView.mListener = null
     }
 
+    override fun onStop() {
+        super.onStop()
+        config.temporarilyShowHidden = false
+    }
+
     private fun tryloadGallery() {
         if (hasWriteStoragePermission()) {
             val dirName = getHumanizedFilename(mPath)
@@ -144,6 +149,7 @@ class MediaActivity : SimpleActivity(), MediaAdapter.MediaOperationsListener {
             R.id.hide_folder -> tryHideFolder()
             R.id.unhide_folder -> unhideFolder()
             R.id.exclude_folder -> tryExcludeFolder()
+            R.id.temporarily_show_hidden -> temporarilyShowHidden()
             R.id.increase_column_count -> increaseColumnCount()
             R.id.reduce_column_count -> reduceColumnCount()
             R.id.settings -> launchSettings()
@@ -243,6 +249,11 @@ class MediaActivity : SimpleActivity(), MediaAdapter.MediaOperationsListener {
             false
     }
 
+    private fun temporarilyShowHidden() {
+        config.temporarilyShowHidden = true
+        getMedia()
+    }
+
     private fun handleZooming() {
         val layoutManager = media_grid.layoutManager as GridLayoutManager
         layoutManager.spanCount = config.mediaColumnCnt

app/src/main/res/menu/menu_media.xml

@@ -32,6 +32,10 @@
         android:id="@+id/exclude_folder"
         android:title="@string/exclude"
         app:showAsAction="never"/>
+    <item
+        android:id="@+id/temporarily_show_hidden"
+        android:title="@string/temporarily_show_hidden"
+        app:showAsAction="never"/>
     <item
         android:id="@+id/increase_column_count"
         android:title="@string/increase_column_count"