* NO cargo workspace at all.

then make two `.code-workspace` files

- one for std code, with `rust-analyzer.linkedProjects` pointing to the top-level std crate (NOT shared deps)
- one for no-std code, with `rust-analyzer.linkedProjects` pointing to the top-level no-std crate (NOT shared deps), and `rust-analyzer.cargo.target` set to the nostd target.