Add commands to explore contents

[Eeems]

It would be interesting to have commands to let you quickly explore the contents of an update image. The couple I could think of would be cat and ls. This would depend on #31 and #32 most likely, but in this scenario, codexctl would automate extracting and mounting to a temporary location, and then cat/ls the output and unmount. The extracted image would be cleaned up at some point too, but probably not right away, unless that performs well.

Performance on a rM device would not be a good idea for mounting to tmpfs though due to the limited ram, so maybe only extract/mount to a specific location on disk under /opt on device?