Summary:
Fixes T9224. This adds:
- A "Default Edit Policy" and "Default View Policy" to Calendar, similar to other applications.
- "Event Host" and "Event Invitees" objects policies.
These policies often end up being redundant (the host can always view/edit, the invitees can always view), but they can be more clear than setting "No One", and "Editable By: Event Invitees" is a legitimately useful policy.
Test Plan:
- Created and edited events.
- Fiddled with defaults.
- Tried to remove myself as the event host for an "Editable By: Host" event, got an error ("you wouldn't be able to edit").
- Tried to remove myself as host/invitee for an "Editable By: Invitees" event, got an error.
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T9224
Differential Revision: https://secure.phabricator.com/D16294
