fix: symlink wit, rather than using relative paths

[rvolosatovs]

This enables downstream builds utilizing cargo vendor, since cargo vendor resolves symlinks before packaging crates up

Closes #133

[rvolosatovs]

Thanks @ipetkov for 100% correct analysis of this ipetkov/crane#271 (comment)

[rvolosatovs]

Alternative, and probably cleaner solution could be adopting something like https://github.com/rvolosatovs/depit once bytecodealliance/wit-deps#9 is implemented, such that the host crate could be self-contained while still benefiting from importing from the shared WIT definitions from the root of the repo

[rvolosatovs]

Alternative solution in #136.

Symlinks AFAIK can be tricky on Windows, so #136 should be a better option

[sunfishcode]

Yeah, I agree that symlinks can be tricky here. Fortunately #136 sounds like a good option.

[rvolosatovs]

Closing in favor of #136