Notifications Update

[eguerrant]

• Change the expiring access notification functions to provide more specific information (eg. list of users who will be losing access to each group instead of just a list of users and a list of groups)
  • The goal is to be able to send notifications along the lines of ' will be losing access to ' instead of the current notifications that are limited more to vague messages like 'A user will lose access next week'
  • Made this change backwards compatible for now so any messages that use the old args should still work
• Add notifications for role owners so that they know when roles they own will be losing access soon
• Updated example notifications

#300 : changes to the Access UI so that role owners are easily able to see roles they own that will be expiring soon under 'Expiring Roles' and will allow them to make a role request from that page

[somethingnew2-0]

Voiced over, we should update the Slack example plugin as well

• https://github.com/discord/access/blob/main/examples/plugins/notifications_slack/notifications.py

We should also verify the example plugins install correctly as well as potentially verify the old version of the plugins ignore the new kwargs for backwards compatibility.

[savathoon]

👍 seems backwards compatible