* GUI module submenu: fix documentation
* GUI module submenu: add submenu_set_selected_item fn
* App iButton: use submenu_set_selected_item to store and set selected item in submenu
* App iButton: swap write and emulate in "saved key menu" scene
* App iButton: file select can now switch to the previous selected file
* App iButton: swap write and emulate indexes in "saved key menu" scene
Co-authored-by: あく <alleteam@gmail.com>