Add nats-net-v2 Connectors

[to11mtm]

Is your feature request related to a problem? Please describe.
I think it would be awesome if the community had a set of Alpakka connectors for nats-net-v2.

Describe the solution you'd like
That we do the needful. I've done some basic scaffolding. General idea being with a clean starting API we can then optimize with a more native stage (unless akkadotnet/akka.net#7028 stalls, in that case maybe we do up front?)

I suppose my ask is ideally "let's get some feedback on what sort of API we think is useful" but will be happy with "sure do the PR and if you take the feedback we will approve".

Describe alternatives you've considered
Per above, we could get fancier with stages....
Inversely speaking, one can see there's nothing fancy in my gist and one could just party on Unfold easily enough, however there's something to be said for providing a polite API for others.

Additional context

Per above I'm happy to own this and do the work :)

I brought this idea up to the Nats .Net folks and they were as always gracious and supportive, It sounds like they may be willing to provide feedback or other input but I will leave those comments via other channels.

Also Note, not sure if a concern: This would be a Net6.0+ only connector, as that is the baseline for the underlying library we are exposing via Alpakka.