Ability to turn off notifications for Issue closed

[mehulkar]

Is your feature request related to a problem? Please describe.
Our Github slack notification channel is noisy

Describe the solution you'd like
I would like to get posts in Slack when a new issue is opened, but not when it's closed. Issues are closed by a team member, and the team generally doesn't need to know. It would also be fine to post an emoji response instead of a new message.

Describe alternatives you've considered
N/A

Additional context
N/A