Create npm-including version of node transport .nupkg in emsdk

[akoeplinger]

We currently consume runtime.<RID>.Microsoft.NETCore.Runtime.Wasm.Node.Transport in the runtime repo. This package is built in dotnet/node, while we also have Microsoft.NET.Runtime.Emscripten.5.0.6.Node.<RID> which we actually ship. The only difference is the latter is missing npm.

We should create an internal/transport package that includes npm in the emsdk repo since that would simplify the flow (right now we need to have a kind of weird node -> VMR subscription for CoherentParentDependency between runtime/emsdk).

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