Leave `tootctl accounts cull` to simply check removed accounts from
live domains, and skip temporarily unavailable domains, while listing
them in the final output for further action.

Add `tootctl domains purge DOMAIN` to be able to purge a domain from
that list manually

* Move more tasks to tootctl

- tootctl feeds build
- tootctl feeds clear
- tootctl accounts refresh

Clean up exit codes and help messages

* Move user modifying to tootctl

* Improve user modification through CLI, rename commands

add -> create
mod -> modify
del -> delete

To remove ambiguity

* Fix code style issues

* Fix not being able to unset admin/mod role