This changes the recipe for client-side blazor to use similar primitives
to server side applications.
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I ignored auto-rebuild support because it's currently dead code until we
have that in VS. If we add auto-rebuild to ASP.NET Core - we'd probably want
to make that a separate gesture inside `IsDevelopement()` like other
dev-time features anyway.
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The static files hookup is a special thing because creating the file
server for a client-side Blazor app involves some non-trivial work. We
plan to make this better in the future.
What's nice about this pattern is that the implementation is pretty
simple and literal, and it scales fine if you have multiple Blazor
client-side apps.
I didn't provide a lot of options here, it's pretty much the same as
UseBlazor.
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I feel pretty good about the wireup with routing to use the
`index.html` from the client app. I think it's pretty to-the-point.