Listen capabilities

[giacomocavalieri]

It would be really nice if pgo allowed one to listen to Postgres channels

• https://www.postgresql.org/docs/current/sql-listen.html
• https://www.postgresql.org/docs/current/sql-notify.html

[tsloughter]

Forgot to reply to this, sorry. Funny enough, I was actually planning on working on that the other day but got sidetracked by closing out existing PRs to pgo and pg_types. I want to do this, yes. Would love thoughts from those interested on an API