Add support for the experimental wasi-crypto APIs (#2597)

* Add support for the experimental wasi-crypto APIs

The sole purpose of the implementation is to allow bindings and
application developers to test the proposed APIs.

Rust and AssemblyScript bindings are also available as examples.

Like `wasi-nn`, it is currently disabled by default, and requires
the `wasi-crypto` feature flag to be compiled in.

* Rename the wasi-crypto/spec submodule

* Add a path dependency into the submodule for wasi-crypto

* Tell the publish script to vendor wasi-crypto

ci/run-experimental-x64-ci.sh

@@ -14,6 +14,7 @@ cargo $CARGO_VERSION \
             --all \
             --exclude wasmtime-lightbeam \
             --exclude wasmtime-wasi-nn \
+            --exclude wasmtime-wasi-crypto \
             --exclude peepmatic \
             --exclude peepmatic-automata \
             --exclude peepmatic-fuzzing \

ci/run-wasi-crypto-example.sh

@@ -0,0 +1,10 @@
+#! /bin/bash
+
+set -e
+
+RUST_BINDINGS="crates/wasi-crypto/spec/implementations/bindings/rust"
+pushd "$RUST_BINDINGS"
+cargo build --release --target=wasm32-wasi
+popd
+
+cargo run --features wasi-crypto -- run "$RUST_BINDINGS/target/wasm32-wasi/release/wasi-crypto-guest.wasm"