[trivy] Add Trivy action

.github/workflows/trivy.yaml

@@ -0,0 +1,14 @@
+name: dsp-appsec-trivy
+on: [pull_request]
+
+jobs:
+  appsec-trivy:
+    # Parse Dockerfile and build, scan image if a "blessed" base image is not used
+    name: DSP AppSec Trivy check
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: broadinstitute/dsp-appsec-trivy-action@v1
+        with:
+             context: .
+             dockerfile: orchestration/Dockerfile