Migrate CSAT survey to Github action from probot.

[shmishra99]

Changes in this PR:

1. Add file constant.js for script level constant values.
2. Add file CSAT.yml to invoke the workflow and call the script when closed event occur.
3. Add file staleCSAT.js when stale workflow closes issue then invoke the script.
4. Update file stale.yml to invoke staleCSAT.js script for survey link.

Thanks.