KAZOO-3191 allow checkout/checkin of workers with pool name, allow

broker on wh_amqp_worker
Might as well make this:

```erlang
cast(Req, PubFun) ->
    cast(Req, PubFun, wh_amqp_sup:pool_name()).

cast(Req, PubFun, Pool) ->
    ....
```