1. Proposed title of this feature request
Quay Image expiring event triggers

2. What is the nature and description of the request?
Create image event triggers for Images expiring within 30/15/7/3/1 day(s). Then notify via email, Slack webhooks, and ect.  My customer would like to be able to do this at an repository level. 

3. Why does the customer need this? (List the business requirements here)
The customer needs to warn their users so that their images are not pulled out from under them.

4. List any affected packages or components.
event triggers