Modify glotter workflow to check for changed code files

[rzuckerm]

• Add tj-actions/changed-files to check for changed code files
• If no code changes, just do nothing but echo a message indicating no code changes
• Also, don't run glotter for a push event that has no code changes
• I fixed Glotter workflow status check cannot be enabled #3909

[jrg94]

We'll give it a go! See how it works.