Update benchmarks, add to CI (#988)

.github/workflows/test-suite.yml

@@ -58,3 +58,10 @@ jobs:
       run: sudo npm install -g ganache-cli
     - name: Run the beacon chain sim
       run: cargo run --release --bin simulator beacon-chain-sim
+  check-benchmarks:
+    runs-on: ubuntu-latest
+    needs: cargo-fmt
+    steps:
+    - uses: actions/checkout@v1
+    - name: Typecheck benchmark code without running it
+      run: make check-benches