to_url
The LSP will need this to unify code paths between WASM and binary builds.
Nothing serious in there.
Get the full path before deciding what to do.
Add some code to do platform-independent path processing. This is necessary aas WASM does e.g. not have any absolute paths and such and the compiler tended to produce wrong results in that case. Side-effect: We no longer need to depend on `dunce`
