Add mod backup functionality

[DanTheMan827]

This allows copying the installed mod from the device back into a qmod file.

[Lauriethefish]

There are a few warnings in the build (unused exceptions) that it would be nice to get fixed.
I'd also appreciate it if the temp folder could be implemented as a class in QP instead of a package - I just don't want to add another dependency if at all possible. Given that qp already has a TempFile class, this would make most sense.