Making IManagementClient.GetAsync (and Put, Post, Delete) APIs public.

[inikulshin]

It'll help developers to use ManagementClient even in cases, EasyNetQ doesn't implement some RabbitMQ Management HTTP API (e.g. new /api/stream/... of rabbitmq_stream_management plugin), or implements some API partially (e.g. PolicyDefinition before #281), or implements API for specific RabbitMQ versions only.

It's essential for developer's custom management plugins that may extend basic RabbitMQ Management HTTP API (like rabbitmq_stream_management, rabbitmq_shovel_management or rabbitmq_federation_management).

And last, but not the least: it may reduce IManagementClient public API to O(1) methods, making all current public methods just an extensions.

[inikulshin]

@Pliner @zidad @micdenny @luigiberrettini FYI

[zidad]

Would be fine my me. I would also be interested in changing the management client to be more in line with a statically typed HTTP client, so the constructor can be simplified:

https://timdeschryver.dev/blog/refactor-your-net-http-clients-to-typed-http-clients

[inikulshin]

Implemented in #319