Adds a GitHub Action to notify when preview link is live

[AlannaBurke]

Description

Adds a GitHub Action to notify when preview link is live. Waits up to 40 minutes. I did test this locally to the extent that i could.

Checklist

• [ ] The issue that is being fixed is referred in the description (see above "Fixes #ISSUE_NUMBER")
• [ ] Only one issue is addressed in this pull request
• [ ] Labels from the issue that this PR is fixing are added to this pull request
• [ ] No unnecessary issues are included into this pull request.