update to WASI 0.2.1

[rvolosatovs]

1. Ran update-wasi.sh
2. Manually copied wasi:http 0.2.1, since the script did not update that
3. Manually updated WIT and rust refs to use 0.2.1
4. Rebuilt the adapters using build-adapter.sh
5. Added more error context because I've accidentally updated wasi:config to 0.2.1, which is still in draft - it was really difficult to find the issue without this. Happy to drop the commit and/or split into a separate PR
6. Updated dependencies

[rvolosatovs]

FWIW, I was unable to use wasi-virt for my use case (bytecodealliance/wasm-tools#1811), but this issue was already reported in May (bytecodealliance/wasm-tools#1565), so it could not have been introduced by this PR

[guybedford]

Thank you for working through this @rvolosatovs this is great, I appreciate it was a tough upgrade path. The extra error context will definitely help in future too.

Upgrading to WAC instead of wasm-tools compose might be sensible for WASI Virt at this point, as I'm not sure what the maintenance status is for wasm-tools compose (WAC wasn't around when WASI Virt was first written).