ci: upload wit tar for releases

[ricochet]

Add new job to create and upload a wasi-wit-VERSION.tar.gz artifact
to GitHub releases containing consolidated WIT files for each proposal.

Note each proposal will include it's deps. These are duplicated across
proposals to keep each proposal self-contained.

NOTE: rc tarballs will fail until we have an updated wkg see #2434

Closes #875

[alexcrichton]

Looking over the 0.2.10 release to double-check on this, the current structure is:

wasi-wit-0.2.10
wasi-wit-0.2.10/http
wasi-wit-0.2.10/http/http.wit
wasi-wit-0.2.10/http/deps
wasi-wit-0.2.10/http/deps/clocks.wit
wasi-wit-0.2.10/http/deps/cli.wit
wasi-wit-0.2.10/http/deps/random.wit
wasi-wit-0.2.10/http/deps/io.wit
wasi-wit-0.2.10/random
wasi-wit-0.2.10/random/random.wit
wasi-wit-0.2.10/io
wasi-wit-0.2.10/io/io.wit
wasi-wit-0.2.10/clocks
wasi-wit-0.2.10/clocks/clocks.wit
wasi-wit-0.2.10/clocks/deps
wasi-wit-0.2.10/clocks/deps/io.wit
wasi-wit-0.2.10/sockets
wasi-wit-0.2.10/sockets/deps
wasi-wit-0.2.10/sockets/deps/clocks.wit
wasi-wit-0.2.10/sockets/deps/io.wit
wasi-wit-0.2.10/sockets/sockets.wit
wasi-wit-0.2.10/filesystem
wasi-wit-0.2.10/filesystem/filesystem.wit
wasi-wit-0.2.10/filesystem/deps
wasi-wit-0.2.10/filesystem/deps/clocks.wit
wasi-wit-0.2.10/filesystem/deps/io.wit
wasi-wit-0.2.10/cli
wasi-wit-0.2.10/cli/cli.wit
wasi-wit-0.2.10/cli/deps
wasi-wit-0.2.10/cli/deps/filesystem.wit
wasi-wit-0.2.10/cli/deps/clocks.wit
wasi-wit-0.2.10/cli/deps/sockets.wit
wasi-wit-0.2.10/cli/deps/random.wit
wasi-wit-0.2.10/cli/deps/io.wit

would it be possible to change that instead to:

wasi-wit-0.2.10
wasi-wit-0.2.10/http.wit
wasi-wit-0.2.10/random.wit
wasi-wit-0.2.10/io.wit
wasi-wit-0.2.10/clocks.wit
wasi-wit-0.2.10/sockets.wit
wasi-wit-0.2.10/filesystem.wit
wasi-wit-0.2.10/cli.wit

Not urgent by any means, but that should make consumption a bit easier

[ricochet]

One key property was to keep each proposal self-contained, which required including the deps otherwise consumers will need another tool to work as a deps-solver. The idea being folks could ignore/remove the deps folder if that's not required for their use. The deps dir per proposal is what forces this into a non-flat structure.

If we want to remove that property of the artifact for some other ergonomic need, I'd like to understand it a little more. I like that individual proposals can be dropped in with existing tooling and work today and this continues the modularity goal of wasi proposals vs treating them as a monolith.

[alexcrichton]

Ok that makes sense yeah. I was thinking we'd just splat the tarball's contents into a deps/*.wit location and it'd be easier than rooting around folders, but on second thought I like the deps being "auto trimmed" in this representation. Disregard me!