Added .NET SDK examples to serialization document

[WhitWaldo]

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Description

The SDK serialization page claimed that only Java uses JSON serialization. To my knowledge, that's not accurate at all - all of the languages use JSON, though there have been recent requests for other serialization approaches. Regardless... while supposedly addressing serialization requirements across the solution, it only provided Java-specific examples. This PR adds .NET examples that are current (for now) to the 1.16 release.

Issue reference

Please reference the issue this PR will close: #4595

[github-actions]

Stale PR, paging all reviewers

[github-actions]

Stale PR, paging all reviewers

[github-actions]

Stale PR, paging all reviewers

[WhitWaldo]

@alicejgibbons Any chance you could review this?

[msfussell]

LGTM but will also let @alicejgibbons comment

[alicejgibbons]

Thanks Whit, big improvement but just a couple small things.

[alicejgibbons]

I also don't think that this invokeActorMethod is correct anymore (unless you're using springboot?). @cicoyle can you take a peek at this actors example?

[cicoyle]

Good call out - If Whit has the bandwidth and would like to update the Java code samples that would be great, but given this PR is for .NET, Im fine with proceeding with this PR and opening follow up issues to ensure the java sdk docs are up to date. I think that would be the best path forward to ensure proper prioritization of the work and not halt this PR that is updating .Net. We should definitely update the Java SDK documentation to align more clearly with our working examples in DemoActorClient.java and ActorTurnBasedConcurrencyIT.java.

[WhitWaldo]

Haha, one thing I don't have is much bandwidth. I've never used the Java SDK and it seems to be receiving quite a few updates based on the flurry of PR notifications I've been receiving.

I would prefer to merge as-is if that's acceptable. I noticed while browsing around the other day that there are several other examples across the docs that I want to update (both for .NET and add JS samples throughout), so this is going to be far from the first of these.

[cicoyle]

I created this issue to track this

[cicoyle]

I realize that this PR is intended to update the .NET docs, but can we please at a minimum take the client.invokeMethod code suggestion in with this PR?

We can open follow up issues for the other mentioned java docs getting updated to not halt this PR for something its not intending to add.

[cicoyle]

Thank you!