Replace copilot-setup.sh with copilot-setup-steps.yml workflow

Co-authored-by: stephentoub <2642209+stephentoub@users.noreply.github.com>

Author: Copilot

.github/copilot-setup.sh

@@ -0,0 +1,25 @@
+name: Copilot Setup Steps
+
+on: workflow_dispatch
+
+jobs:
+  setup:
+    runs-on: ubuntu-latest
+    
+    steps:
+    - name: 🔧 Set up .NET SDK
+      uses: actions/setup-dotnet@d4c94342e560b34958eacfc5d055d21461ed1c5d # v5.0.0
+      with:
+        dotnet-version: |
+          10.0.100-rc.1.25451.107
+    
+    - name: 📋 Display .NET SDK information
+      run: |
+        echo "=== Installed .NET SDKs ==="
+        dotnet --list-sdks
+        echo ""
+        echo "=== Current .NET SDK Version ==="
+        dotnet --version
+        echo ""
+        echo "=== .NET Info ==="
+        dotnet --info