[acogoluegnes]

This commit implements the "AMQP Enforcing Connection Uniqueness
Version 1.0" specification extension. It introduces cluster-wide
tracking of AMQP 1.0 client connections to ensure only a single
connection can be established for a given container-id per vhost.

Implementation Details:

• Introduces rabbit_sole_conn, a gen_server that manages
  a dedicated Khepri (Raft-based) store to track active connection
  leases across the cluster.
• Updates rabbit_amqp_reader to parse the sole-connection-for-container
  capability and coordinate with the sole connection registry during
  the initial AMQP 1.0 open handshake.
• Enforces two conflict resolution policies defined by the spec:
  • refuse-connection: Rejects the new connection with an invalid-field
    condition if an existing connection holds the lease.
  • close-existing: Terminates the existing connection with a
    resource-locked condition and grants the lease to the new connection.
• Applies a weak detection policy, enforcing uniqueness only when
  explicitly requested by the client via connection properties.

Security and Semantics:

• Connection leases are scoped strictly to the vhost and container-id.
• Enforces user ownership: a lease can only be taken over or replaced
  (close-existing) by the same authenticated user. Attempts by different
  users to hijack an active container-id are unconditionally refused.

Operability:

• Adds rabbitmqctl sole_connection_status to inspect the Raft consensus
  state of the sole connection registry.
• Adds rabbitmqctl sole_connection_force_delete to allow operators to
  manually evict stale leases if necessary.
• Introduces operator commands wipe and start for low-level recovery
  and bootstrapping of the Khepri store.

Configuration Parameters:

• Expose the three configuration parameters of rabbit_sole_conn
  in rabbitmq.conf under the sole_connection prefix.
• sole_connection.tick_interval -> rabbit.sole_connection_tick_interval
• sole_connection.leader_wait_retry_timeout -> rabbit.sole_connection_leader_wait_retry_timeout
• sole_connection.default_timeout -> rabbit.sole_connection_default_timeout

[acogoluegnes]

@michaelklishin We removed the protocol prefix (I updated the PR description, it was outdated, but the code is correct). We use only the sole_connection prefix, as the feature could be used for other protocols. So it is no longer specific to AMQP 1.0, so using an amqp10. prefix would not be relevant.

[dumbbell]

A couple minor comments