Create separate "Accept" and "Decline" transactions for Calendar
Ref T9275. Currently, there's a single "invite" transaction type for managing Calendar invites, and it takes a map of invitees to status.
This isn't great for EditEngine or API access, since it lets you set anyone else to any status and we can't reuse as much code as we can with a simpler API.
Make "Accept" and "Decline" separate actions which affect the actor's invite, so "invite" can be a simpler transaction which just invites or uninvites people.
- Joined/accepted/declined an event invitation.
- Edited event invitees.
Reviewed By: chad
Maniphest Tasks: T9275
Differential Revision: https://secure.phabricator.com/D16272