Team is notified when a contributor posts a comment to a GitHub issue

[MisRob]

Summary

Create a GitHub action that sends a Slack notification to #dev-community channel whenever someone who's not a member of the Learning Equality Team comments on a GitHub issue

Acceptance criteria

• A notification is sent to #dev-community Slack channel any time (not just a first time) an external person comments on a GitHub issue
• The notification is not sent when an external person comments on a pull request
• The action uses only official GitHub and Slack 3rd party actions. Other actions can be used for inspiration, but the logic should be implemented by us (for security and to prevent regressions when updating versions).

Tasks

Preview Give feedback

1. On issue_comment, find out if the comment was done on a pull request or an issue (issue_comment on issues only or pull requests only). Continue only if it's an issue comment.
2. Find out if an author of the issue comment is a member of the Learning Equality Team. See comment.author_association (hidden in "Properties of comment" toggle) and CommentAuthorAssociation. Continue only if the author is not MEMBER and neither OWNER.
3. Send the notification about the comment to the #dev-community Slack channel. The official Slack action can be used.

[marcellamaki]

The first step of this would just be investigation and proposing an implementation

[vkWeb]

@MisRob closing this since its done I feel. 🎉