Add package for consuming Blazor framework assets

[MackinnonBuck]

Adds a new package Microsoft.AspNetCore.Assets.Pack (final package name open for discussion), which includes Blazor framework files as static web assets. A follow-up change in the SDK will add an implicit reference to this package in any Blazor project targeting .NET 10 or later.

This change means that blazor.*.js files will get compressed and fingerprinted automatically.

Fixes #58783

[javiercn]

Microsoft.AspNetCore.Assets.Pack

Haven't looked at the PR yet, but we should probably name it in a way that is related to the framework reference and include Internal in some way. Microsoft.AspNetCore.App.Internal.Assets

It might also be interesting if we find a way of precluding explicit consumption through a package reference (we can have MSBuild logic to potentially detect that scenario).

[wtgodbe]

Why library?

[javiercn]

Why not? This is not producing any exe/dll

[wtgodbe]

Wanted to make sure it's intentional, I don't know off the top of my head if this controls any behavior we care about

[javiercn]

No, it's conceptually a library

[ViktorHofer]

I'm having troubles getting this to build inside the VMR. Don't we need something similar to

aspnetcore/src/Components/WebView/WebView/src/Microsoft.AspNetCore.Components.WebView.csproj

Lines 66 to 72 in 8d0f798

	<!-- blazor.webview.js should exist after eng/Npm.Workspace.nodeproj builds. Fall back if not. -->
	<Target Name="_CheckBlazorWebViewJSPath" AfterTargets="ResolveProjectReferences" Condition=" !EXISTS('$(BlazorWebViewJSFile)') ">
	<Warning Text="'$(BlazorWebViewJSFile)' does not exist. Falling back to checked-in copy." />
	<PropertyGroup>
	<BlazorWebViewJSFile>..\..\..\Web.JS\dist\Release\$(BlazorWebViewJSFilename)</BlazorWebViewJSFile>
	</PropertyGroup>
	</Target>

as a fallback?

[ViktorHofer]

OK my issue with building this inside the VMR is unrelated to this change. But I wonder if a fallback should still get added as the other project has it.

[ViktorHofer]

So with this change I can't build the repo anymore if I don't have nodejs installed. Is that intentional?