Until `rbw` gets support for Yubikey 2FA, I still need a decent way to
query for my passwords on the command line...
This wrapper program should be good enough for basic usage with programs
that need a password command.
Also make it the prime overlay instead of the extended 'lib'.
The reason for `pkgs` not being structured as an overlay, but simply
taking `pkgs` as an argument is to allow it to be used as a NUR package
set, if I wanted to.
