Add support for more pub-sub protocols

[dborovcanin]

Is your feature request related to a problem? Please describe.

I'm trying to use mGate to integrate Magistrala users and clients and topic (channel) management to my existing platform that is already using the underlying message broker.

Describe the feature you are requesting, as well as the possible use case(s) for it.

I'd like to use mGate as a universal proxy tool to directly access the message broker such as NATS, RabbitMQ, Kafka, Redis, and others. Ideally, I'd use mGate to transparently enforce access control or some other policies on my messaging, with minimal overhead from the application side (i.e. only setting up the auth token). This implies that mGate should "speak" protocols the underlying broker is using, similar to MQTT and HTTP.
Protocols we should target are:

• Kafka protocol
• AMQP
• MQTT 5.0 (see Add support for MQTT v5.0 #75)
• NATS protocol

Most of these protocols are TCP/IP-based.

Indicate the importance of this feature to you.

Must-have

Anything else?

Ideally, the one should be able to use mGate in three ways:

• As a sidecar proxy that is deployed alongside the service for which it is enforcing policies
• As a standalone service that can serve multiple protocols and proxy them to respective backends
• As a library (a wrapper around respective pub/sub client libraries)