Auto-generate all Async and Sync extensions of IManagementClient.

[inikulshin]

Async - all those one-liners that accept Vhost, Queue, etc. parameters and call Async methods/extensions with string parameters.
Sync - all one-liners that call Async methods/extensions with exactly the same parameters continued with .GetAwaiter().GetResult().

I already have a code that generates both (83 Async and 163 Sync extensions), but I'm not sure what to do:

1. Push autogenerated extension files only and continue to maintain them manually.
2. Push autogenerated extension files and generator code in a separate solution to help to maintain extension files semi-automatically in rare(?) case of API changes.
3. Push generator code only as a part of main solution - however it'll require additional project and some ugly postbuild tasks...

[zidad]

Interesting! Are you not using a Roslyn generator with attributes, because then it should be possible to generate build time without needing any files at all?

Alternatively, I was thinking this library could benefit from https://github.com/reactiveui/refit attributes on the interfaces, so we don't need any concrete implementation at all in our code base.

[inikulshin]

I used Microsoft.CodeAnalysis.CSharp for syntax tree generation, but I didn't know how to create generator right.
Now I'm sure it should be option (3) with source generator https://learn.microsoft.com/en-us/dotnet/csharp/roslyn-sdk/source-generators-overview.

[inikulshin]

@zidad I won't create any additional PR before my other PRs are closed.

[zidad]

That's fair enough! Sorry I'm a bit out of the loop in de EasyNetQ projects but I'll have a look now

[inikulshin]

Implemented in #304