Keep InventoryEditor component mounted even when dialog is closed

[taesungh]

The InventoryEditor component is rendered only when editorDialogOpen is set to true in InventorySelector. This causes the editor to refetch the IPA skeleton data files each time the editor is opened (although the network requests should be cached). This can be avoided by keeping the component mounted and allowing the open prop of the Dialog element inside to control the display. This will also allow the last selected tab (consonants, other, vowels) to stay selected when closing and reopening the editor.