feat(p3-shim): sync with latest 0.3.0 rc

[andreiltd]

This update p3-shim implementation to the latest 0.3.0 proposal:

• wasi:http/proxy -> wasi:http/service,
• wall-clock -> system-clock
• set-stdin -> read-via-stream
• set-stdout -> write-via-stream
• set-stderr -> write-via-stream
• filesystem requestedIntegritySync -> requestedWriteSync
• request/response body method is now static consume-body function
• http client request -> send
• use array instead of object for tuples consistently
• use wkg to get the latest wit files - the format that wkg uses change the p3 structure and there is a single package file now - I found that if I try to use wkg fetch wkg do not preserve comments so probably it goes through binary image while using wkg get preserves command but has different file layout.

[vados-cosmonic]

LGTM 🚀

Thanks for the update @andreiltd !