update WASI submodule (#3025)

* wasi-common: update wasi submodule

This updates the WASI submodule, pulling in changes to the witx crate,
now that there is a 0.9.1 version including some bug fixes. See
WebAssembly/WASI#434 for more information.

* wiggle: update witx dependencies

* publish: verify and vendor witx-cli

* adjust root workspace members

This commit removes some items from the root manifest's workspace
members array, and adds `witx-cli` to the root `workspace.exclude`
array.

The motivation for this stems from a cargo bug described in
rust-lang/cargo#6745: `workspace.exclude` does not work if it is nested
under a `workspace.members` path.

See WebAssembly/WASI#438 for the underlying change to the WASI submodule
which reorganized the `witx-cli` crate, and WebAssembly/WASI#398 for the
original PR introducing `witx-cli`.

See [this
comment](https://github.com/bytecodealliance/wasmtime/pull/3025#issuecomment-867741175)
for more details about the compilation errors, and failed alternative
approaches that necessitated this change.

N.B. This is not a functional change, these crates are still implicitly
workspace members as transitive dependencies, but this will allow us to
side-step the aforementioned cargo bug.

Co-Authored-By: Alex Crichton <alex@alexcrichton.com>

Co-authored-by: Alex Crichton <alex@alexcrichton.com>

scripts/publish.rs

@@ -176,7 +176,7 @@ fn read_crate(manifest: &Path) -> Crate {
     } else {
         version.clone()
     };
-    if ["witx", "wasi-crypto"].contains(&&name[..]) {
+    if ["witx", "witx-cli", "wasi-crypto"].contains(&&name[..]) {
         publish = false;
     }
     Crate {