Support custom wasm paths

[matprec]

The generated wasm loader will only load wasm files relative to the html page. This is a problem if the wasm file is in a static directory (mysite.app/static_path/awesome.wasm), served by a third party framework. Currently i have to manually adjust the path to prepend '/static_path/' in the generated file here.

I'd propose to make this path configurable in Web.toml.

[Pauan]

This might also solve some problems I've had with Chrome Extensions, so this gets a big :+1: from me.

[koute]

This was something I did plan to add, but not WASM-specific - you'd set the path in your Web.toml to where your .js file would be generated (e.g. with cargo deploy) and served from with the implication that the .wasm file would be right next to it on non-asmjs targets.

Would that work for you?

[matprec]

If you mean that the wasm file will be loaded from the same absolute path, then yes!