Replace old core Wasm module linking support with new component model linking support

[fitzgen]

https://github.com/WebAssembly/component-model

This will require using interface types for the initialization function. Not 100% clear whether we want to keep the same init function interface (no params and no returns) or not. Probably? (Although I think @lukewagner also had ideas of "building in" the pre-initialization model into components. Don't think that has been fleshed out yet tho.)