Make it (a tiny bit) easier to run your own collab (#9557)

* Allow creating channels when seeding
* Allow configuring a custom `SEED_PATH`
* Seed the database when creating/migrating it so you don't need a
  separate step for this.

Release Notes:

- N/A

script/seed-db

@@ -1,4 +1,4 @@
 #!/bin/bash
 set -e
 
-cargo run --quiet --package=collab --bin seed -- $@
+cargo run -p collab migrate