Add epic_fs_is_attached(), os.fs_is_attached(), and make the menu automatically return from USB mode

Add a new API call to check whether the filesystem is attached to card10 or to a connected USB host (in which case it is unavailable to card10). Make the menu check this and automatically exit "USB storage mode" when a host ejects the device.

changed milestone to %v1.18

added 1-Additional-Feature 3 - Preload 3-Epicardium 3-Pycardium labels

Looks good to me! Thanks for keeping our codebase clean.

However, I'm only a bot - so a human will still have to approve this request.

assigned to @schneider

merged

mentioned in commit b0e0988f