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

.github/workflows/main.yml

@@ -274,6 +274,7 @@ jobs:
             --exclude lightbeam \
             --exclude wasmtime-lightbeam \
             --exclude wasmtime-wasi-nn \
+            --exclude wasmtime-wasi-crypto \
             --exclude peepmatic \
             --exclude peepmatic-automata \
             --exclude peepmatic-fuzzing \
@@ -351,6 +352,21 @@ jobs:
         env:
           RUST_BACKTRACE: 1
 
+  # Build and test the wasi-crypto module.
+  test_wasi_crypto:
+    name: Test wasi-crypto module
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+      with:
+        submodules: true
+    - run: rustup target add wasm32-wasi
+    - name: Install Rust
+      run: rustup update stable && rustup default stable
+    - run: ./ci/run-wasi-crypto-example.sh
+      env:
+        RUST_BACKTRACE: 1
+
   # Verify that cranelift's code generation is deterministic
   meta_determinist_check:
     name: Meta deterministic check
@@ -459,6 +475,7 @@ jobs:
             --exclude lightbeam \
             --exclude wasmtime-lightbeam \
             --exclude wasmtime-wasi-nn \
+            --exclude wasmtime-wasi-crypto \
             --exclude peepmatic \
             --exclude peepmatic-automata \
             --exclude peepmatic-fuzzing \