(#12349) Order stderr output to fix acceptance test for module list

The stdout was ordered, but not the stderr, so the acceptance tests that
passed on my system failed when run by CI.

To order the stderr output I changed the format of the method that gets
unmet dependencies to be a hash that contains the dependency module name
in addition to the error message so that I could sort by that name.

There's also some additional documentation updates to the list command
to show example error output for unmet dependencies.

I changed the unsatisfied_dependencies method to unmet_dependencies
since in future changes that's how dependency problems will be described
to the user, and it's shorter.