fix: Build bindings from the crate directory
requested to merge SalvatoreT/uniffi-kotlin-multiplatform-bindings:salvatoret/build-from-crate into main
Right now, the bindgen task always runs from the root of the project.
Unfortunately that means that if the Cargo.toml file is in a /uniffi
folder, you need to also have a Cargo.toml workspace file at the root of
the project to point to the nested uniffi folder.
This change follows the convention from the other commands which run from the crate directory (and it doesn't change the API).