Improve connection limits, introduce per-protocol connection limits

This is an umbrella issue for a number of closely related discussions on [the limits RabbitMQ supports](https://www.rabbitmq.com/docs/limits) or should support with @the-mikedavis @ansd @acogoluegnes. ## Problem Definition The VMware, Inc. part of the core team proposes reviewing our limits to eventually (likely before `4.4.0`) converge on the following limits design/structure/separation: 1. Per-user and per-virtual host apply to all protocols 2. `connection_max` covers core protocols (AMQP 1.0, AMQP 0-9-1) 3. `{plugin}.connection_max` covers each plugin protocol, including their Protocol-over-WebSockets variants, so `mqtt.connections_max` will cover both MQTT and MQTT-over-WebSockets Note that most of this design is already in place but given the number of limits and protocols RabbitMQ supports, we need to review that nothing is missing, in particular for the per-user and per-virtual host limits. ## HTTP API If we put the WebSockets-based protocols aside, the HTTP API is not really covered by the above limits and given the request-oriented nature of HTTP (even with persistent connections, even with HTTP/2, HTTP/3), the protective measure here is a Ranch-level connection limit introduced in https://github.com/rabbitmq/rabbitmq-server/pull/7753, https://github.com/rabbitmq/rabbitmq-server/issues/7593. ## Tanzu RabbitMQ Protocols `connections_max` should cover AMQP 1.0-over-Websockets since its a WebSocket variant of the core protocols. ## Remaining Items as a TODO List * [x] Rename `stream.connection_max` to `stream.max_connections` (MK) * [x] Implement `mqtt.max_connections` (https://github.com/rabbitmq/rabbitmq-server/pull/16367) * [x] Implement `stomp.max_connections` (https://github.com/rabbitmq/rabbitmq-server/pull/16368) * [x] Ship [Cuttlefish `3.7.0`](https://github.com/Kyorai/cuttlefish/releases/tag/v3.7.0) * [x] Bump Cuttlefish in RabbitMQ to `3.7.0` (https://github.com/rabbitmq/rabbitmq-server/pull/16389) * [x] Alias `connection_max` in the core broker as `max_connections` (https://github.com/rabbitmq/rabbitmq-server/pull/16414) * [x] Investigate an optimal solution for the HTTP API (https://github.com/rabbitmq/rabbitmq-server/pull/16407)