Refactor build-dev-container.yaml to include FOLDERS_JSON output

- Add echo statement to display FOLDERS_JSON value
- Include FOLDERS_JSON in the matrix output

.github/workflows/build-dev-container.yaml

@@ -21,7 +21,9 @@ jobs:
           FOLDERS=${FOLDERS//\//} # remove trailing slashes
           FOLDERS=${FOLDERS//templates\//} # remove leading 'templates/'
           FOLDERS_JSON=$(echo "$FOLDERS" | jq -R -s -c 'split("\n")[:-1]')
+          echo "FOLDERS_JSON: $FOLDERS_JSON"
           echo "::set-output name=matrix::${FOLDERS_JSON}"
+          
   build:
     runs-on: ubuntu-latest
     strategy: