fix #557, apply the password protection to Manage Hidden Folders

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

@@ -92,9 +92,11 @@ class SettingsActivity : SimpleActivity() {
 
     private fun setupManageHiddenFolders() {
         settings_manage_hidden_folders_holder.setOnClickListener {
+            handleHiddenFolderPasswordProtection {
                 startActivity(Intent(this, HiddenFoldersActivity::class.java))
             }
         }
+    }
 
     private fun setupShowHiddenItems() {
         settings_show_hidden_items.isChecked = config.showHiddenMedia