Allow naming and saving custom inventories via local storage

[taesungh]

When using the inventory editor, the modified inventory is available only for the active session and lost when closing the tab/window. To make it easier to manage multiple custom inventories across sessions, the inventories can be saved to local storage to be available for future sessions. There will need to be a mechanism to name and recall them. Ideally there should also be a warning when selecting another inventory while there are unsaved changes.

• Create a hook for using local storage
• Add a button to save an inventory with a given name
• Show the local inventories in the Select menu along with the default inventories
• Provide a way to delete custom inventories
  • Renaming would also be nice but might be more complicated