[wasm] Enable relinking of the wasm binary at build time

[CoffeeFlux]

This lets us minimize the app size, and in particular lets us potentially link out a bunch of code held alive by unused pinvokes and dependencies.

It will require emscripten to be present on user machines and expands the size of the runtime pack.

cc: @vargaz

[CoffeeFlux]

This is currently implemented with AOT specifically for the console sample, and needs another option to get that working without AOT as well. For broader usage, we're still figuring out the right way to plumb it through msbuild.

[CoffeeFlux]

Fixed by #45072