Consolidate and make channels `name`s (`client_id` / `service_id`) optional

[llucax]

What's needed?

A clean and consistent interface to create channels, and one that doesn't require to pass strings used for debugging only.

Proposed solution

• Join both client_id and service_id from Anycast constructor into an name argument to match Broadcast.

• Make name optional

  If name is None I would just generate a uuid or just id() (in a distributed context, uuid will make any unlikely collision even more unlikely).

Use cases

No response

Alternatives and workarounds

No response

Additional context

No response