Add implicit reference to Microsoft.AspNetCore.App.Internal.Assets

[MackinnonBuck]

Follow up to dotnet/aspnetcore#58721

[MackinnonBuck]

Tested locally by building a local version of the SDK, manually making changes to the generated Microsoft.NETCoreSdk.BundledVersions.props file, copying the SDK to a locally-built version of ASP.NET Core, undoing the workaround here, and running a project generated by the Blazor Web App project template. Everything seemed to work (the fingerprinted blazor.web.js file was loaded and the binlog showed that the implicit project reference was being added), so I'm going to mark this PR as ready-for-review.

[javiercn]

This is the only part I'm not 100% sure about. You can have an SDK and multiple runtimes. Meaning that you can have an install that has 1.0.0, 1.0.1, and 1.0.2 installed. 1.0.2 might be bundled, but your app might be using <FrameworkReference="Microsoft.AspNetCore.App" Version="1.0.0" /> or have it pinned in the global.json.

In that case shouldn't we respect that?

@maraf do you have any thoughts?

[maraf]

My understanding is that when we are building an app, we are always using the bundled versions; otherwise the rest of the items wouldn't work correctly as well.

[javiercn]

@maraf but it depends on whether you are pinning explicitly to a previous runtime, isn't it?

[javiercn]

Let's go with this for now