Inventory improvements

This update brings multiple big improvements to the Inventory section of Rentle Admin! Bulk actions: tired of editing your articles one by one? We knew you were, so we added some convenient bulk actions for the most common use-cases. Now you can select the articles you want to edit, and change the status, allocation or store location for all of them with one click. SKU page: we added a convenient shortcut to the SKU page, where you can quickly add more Articles for that SKU. Performance improvements: inventory-related actions should be snappier and more responsive across the board - especially when working with large inventory sizes