Make `teos-cli get_user` return locators in `appointments`

[sr-gi]

Currently, get_user_info returns a list of UUIDs when requesting info about a user, and therefore, teos-cli get_user display those. This is a bit counter-intuitive given, for the user's/admin's sake, everything is identified by locator. Also, UUIDs can be recreated from the Locator and the given user, so we could just simply display Locator's here.

Do this once #190 is landed, given it'll make more sense once we don't have any data in memory.

[aruokhai]

Hey, I think i would work on this as my first contribution