Blazor Server reconnection coverage

[guardrex]

Fixes #32789
Addresses #32692
Addresses #31909

Mackinnon, I'm blocked at the moment on working on the What's New side of this until another PR merges, but I'll have the What's New part for this updated (some coverage was placed that I'll be touching up) by EOD on a separate PR.

UPDATE: Not blocked any longer on What's New. I'll take care of it after the four reference article PRs are merged.

WRT this coverage: It seems like we'd call the default logic "a computed backoff strategy" instead of "an exponential backoff strategy." However, your custom example is exponential, so I retain that language for the example.

I was curious about the default logic, and I think devs will be curious, too. The link goes here ...

https://github.com/search?q=repo%3Adotnet%2Faspnetcore%20computeDefaultRetryInterval&type=code

... and that's probably a decent approach for avoiding a hard link with a specific set of line numbers. It will work well as long as the FN name computeDefaultRetryInterval is stable. I like the way that it finds the exact line in the file for them when they click on the search result, and I like the way that it would find this FN if it moved to a different file in the future. However, we can pull that link and those remarks if you don't want to risk it breaking at some point.

As usual, the INCLUDE that explains what the link loads follows the link, and the content of that INCLUDE can be seen here ...

https://github.com/dotnet/AspNetCore.Docs/blob/main/aspnetcore/includes/aspnetcore-repo-ref-source-links.md

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aspnetcore/blazor/fundamentals/signalr.md	ASP.NET Core Blazor SignalR guidance

[MackinnonBuck]

It will work well as long as the FN name computeDefaultRetryInterval is stable

Yeah, I think that's probably fine. In the worst case, we accidentally rename it in the future, but we then will likely get reports of a broken link and fix it.

[guardrex]

Try it now, but I'm not sure if that wording is exactly right ... I've been working here from 6am to 8pm non-stop 😩.

[guardrex]

Ok ... all good.

🍻

I'll get this merged as soon as it builds.