Add notifications to builder

[dmccown]

Add the ability for users to subscribe to notifications and alerts related to activity on a plan. A recent request describing what this functionality could look like: #821

[jeremymv2]

Work completed thus far:

• Adds feature-flagged POC for kafka producer to builder api #1533
• [REFACTOR] cloudevents API into builder-events #1540
• eventbus consumer libs and notification service stub #1549
• replace String return type for EventConsumer #1550

[jeremymv2]

Next up:

• add async stream consumer method to EventConsumer #1552
• add event -> webhook emmission to builder-notify #1553

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. We value your input and contribution. Please leave a comment if this issue still affects you.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. We value your input and contribution. Please leave a comment if this issue still affects you.