ci: add revival-start caller (PowerShellOrg/.github#16)

Author: tablackburn

.github/workflows/revival-start.yml

@@ -0,0 +1,17 @@
+name: Start module revival
+on:
+  workflow_dispatch:
+    inputs:
+      steward:
+        description: "GitHub login of the Steward"
+        required: false
+permissions:
+  issues: write
+  contents: read
+jobs:
+  start:
+    # Pinned to the PR branch until PowerShellOrg/.github#16 merges; then @main and drop source_ref.
+    uses: PowerShellOrg/.github/.github/workflows/revival-start.yml@revival-generator
+    with:
+      steward: ${{ inputs.steward }}
+      source_ref: revival-generator