.NET: Harden dotnet-format workflow shell handling (#14201)

Minor robustness and hygiene improvements to how the dotnet-format
workflow passes values to the shell. No functional change to the
formatting behavior.

---------

Copilot-Session: b0794c00-ed83-4259-8d12-26df4b836393

Author: SergeyMenshykh

.github/workflows/dotnet-format.yml

@@ -53,11 +53,14 @@ jobs:
       - name: Find csproj files
         id: find-csproj
         if: github.event_name != 'pull_request' || steps.changed-files.outputs.added_modified != '' || steps.changed-files.outcome == 'failure'
+        env:
+          ADDED_MODIFIED: ${{ steps.changed-files.outputs.added_modified }}
         run: |
           csproj_files=()
           exclude_files=("Experimental.Orchestration.Flow.csproj" "Experimental.Orchestration.Flow.UnitTests.csproj" "Experimental.Orchestration.Flow.IntegrationTests.csproj")
+          set -f
           if [[ ${{ steps.changed-files.outcome }} == 'success' ]]; then
-            for file in ${{ steps.changed-files.outputs.added_modified }}; do
+            for file in $ADDED_MODIFIED; do
               echo "$file was changed"
               dir="./$file"
               while [[ $dir != "." && $dir != "/" && $dir != $GITHUB_WORKSPACE ]]; do
@@ -78,7 +81,8 @@ jobs:
           fi
           csproj_files=($(printf "%s\n" "${csproj_files[@]}" | sort -u))
           echo "Found ${#csproj_files[@]} unique csproj/slnx files: ${csproj_files[*]}"
-          echo "::set-output name=csproj_files::${csproj_files[*]}"
+          echo "csproj_files=${csproj_files[*]}" >> "$GITHUB_OUTPUT"
+          set +f
 
       - name: Pull container dotnet/sdk:${{ matrix.dotnet }}
         if: steps.find-csproj.outputs.csproj_files != ''
@@ -87,8 +91,11 @@ jobs:
       # This step will run dotnet format on each of the unique csproj files and fail if any changes are made
       - name: Run dotnet format
         if: steps.find-csproj.outputs.csproj_files != ''
+        env:
+          CSPROJ_FILES: ${{ steps.find-csproj.outputs.csproj_files }}
         run: |
-          for csproj in ${{ steps.find-csproj.outputs.csproj_files }}; do
+          set -f
+          for csproj in $CSPROJ_FILES; do
             echo "Running dotnet format on $csproj"
-            docker run --rm -v $(pwd):/app -w /app mcr.microsoft.com/dotnet/sdk:${{ matrix.dotnet }} /bin/sh -c "dotnet format $csproj --verify-no-changes --verbosity diagnostic"
+            docker run --rm -v "$(pwd):/app" -w /app mcr.microsoft.com/dotnet/sdk:${{ matrix.dotnet }} dotnet format "$csproj" --verify-no-changes --verbosity diagnostic
           done