Consider restoring the Blazor WebAssembly "hosted" option

[SteveSandersonMS]

We recently removed the --hosted option from the Blazor WebAssembly project template, on the grounds that we considered it unnecessary now that the new blazor template includes support for WebAssembly components on an ASP.NET Core host.

However, there are still clear use cases for dotnet new blazorwasm --hosted:

1. If you want a WebAssembly-everywhere project, like we offered in .NET 7 and earlier, it would be really hard to set that up without a template for it. You'd need to do dotnet new blazor --use-wasm, then make lots of changes to move files into the WebAssembly project.
   • Further, if auth is enabled, how would people even know if they've done it right?
2. If you want an ASP.NET-hosted PWA, this is likely going to be the only way it could work. I think we will not offer a --pwa option on the Blazor Web project, because it couldn't work offline by default (we can't cache all the SSR pages, we don't even have a way to discover them all). If our PWA is to continue meaning "offline-enabled PWA", then that will only be able to work in a WebAssembly-everywhere case, and so we need to use the blazorwasm template for that. If someone wants to combine this with being ASP.NET Core-hosted, they will need blazorwasm --hosted to be brought back.

[mkArtakMSFT]

We're going to bring back the hosted option with an additional log message suggesting that the new template should be preferred in case of it meets all the requirements the developer has.

[AlbertoPa]

Currently the new "Blazor Web App" template does not offer the option to configure a Web API that can be called from WebAssembly. What is the guidance for a WASM app based on the new template to interface, for example, to a database in simple scenarios where there is no clear need for a separate Web API app? It is a common scenario for a client-side app.

[mkArtakMSFT]

Closing this in favor of #50433