feat: add wasm interface

[hasundue]

This PR provides a possible implementation for #27. Documentation would follow if this was likely to be accepted.

Feel free to close this as well as the issue if they don't fit.

[hasundue]

UPDATE: I have implemented per-dependency updating of a lock file in my dependency updater with this PR, where update_workspace_config is used to extract partial locks for each dependency, etc.

Now I'm more likely to withdraw this PR and rewrite it as an internal crate in the tool, because:

• As an outside contributor, I tried to make this PR as less opinionated as possible, resulting in a boring transpiration of the original interface, which is not ergonomic as a TS library.
• Including this PR in the project as a submodule doesn't feel very comfortable.

So please tell me in case anyone want to keep me working on this PR.