Commands that support group filtering output 0 as their matching groups

[angela-tran]

To Reproduce

1. Run littlepay groups to see what groups are available
2. Pick one of these commands: link, unlink, or migrate
3. Comment out its API call so that it doesn't actually run.
   • For example, for link, comment out this line
4. Run your command with any arguments it needs, e.g. littlepay groups link blah
5. Notice that the command output says there were 0 matching groups

Expected result

The output should show which groups were operated on.

Additional context

@angela-tran Great news! Do you know why it's printing the last line?

👥 Matching groups (0): qa, mst

Originally posted by @thekaveman in #49 (comment)