package library as a ES module

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Clear and concise description of the problem

I would like to use the typespec library from a WASI component. It would need the typespec library bundled as a ES module. This would be simliar to how it is bundled for VS Code here, but the rollup output format would need to be es instead of commonjs. As you can see by this hack, there are a few places where things are reliant on Node.js would be to be abstracted. TypeScript made a System interface for that purpose.

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