Add GitHub Copilot setup steps workflow for .NET 9 environment

.github/workflows/copilot-setup-steps.yml

@@ -0,0 +1,40 @@
+---
+name: "Copilot Setup Steps"
+
+# Automatically run the setup steps when they are changed to allow for easy
+# validation, and allow manual testing through the repository's "Actions" tab
+"on":
+  workflow_dispatch:
+  push:
+    paths:
+      - .github/workflows/copilot-setup-steps.yml
+  pull_request:
+    paths:
+      - .github/workflows/copilot-setup-steps.yml
+
+jobs:
+  # The job MUST be called `copilot-setup-steps` or it will not be picked up
+  # by Copilot.
+  copilot-setup-steps:
+    runs-on: ubuntu-latest
+
+    # Use the same .NET 9 container image as the devcontainer
+    container:
+      image: mcr.microsoft.com/devcontainers/dotnet:1-9.0-bookworm
+
+    # Set the permissions to the lowest permissions possible needed for your
+    # steps. Copilot will be given its own token for its operations.
+    permissions:
+      # If you want to clone the repository as part of your setup steps, for
+      # example to install dependencies, you'll need the `contents: read`
+      # permission. If you don't clone the repository in your setup steps,
+      # Copilot will do this for you automatically after the steps complete.
+      contents: read
+
+    # You can define any steps you want, and they will run before the agent
+    # starts. If you do not check out your code, Copilot will do this for you.
+    steps:
+      - name: Verify .NET installation
+        run: |
+          dotnet --version
+          dotnet --info