Add skeleton action for equivalence tests (#31940)

.github/workflows/equivalence-test.yml

@@ -0,0 +1,27 @@
+name: Terraform Equivalence Tests
+
+# This action will execute the suite of Terraform equivalence tests after a
+# tag has been pushed for a new version.
+#
+# For now, it is just a skeleton action that will be populated shortly.
+
+on:
+  workflow_dispatch:
+    inputs:
+      version:
+        required: true
+        description: "the Terraform version to equivalence test, eg. v1.3.1"
+      run-id:
+        required: true
+        description: "the run identifier of a successful `Build Terraform CLI Packages` action that contains artifacts for the target version"
+
+permissions:
+  contents: read
+
+jobs:
+  skeleton-job:
+    name: "Temporary job to be released with real work"
+    runs-on: ubuntu-latest
+
+    steps:
+      - run: echo "Hello, world!"