Allow Calendar imports to be configured with hourly or daily auto-updates
Summary:
Ref T10747. For URI-based (and, in the future, Google-based) imports, we can automatically refresh them periodically.
(In the general case there's no way to get a push notification for an ICS file, so we just have to do this every-so-often.)
Test Plan:
- Set an ICS file to update hourly.
- Used bin/trigger fire --id ... to fire it artificially.
- Saw Calendar update.
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T10747
Differential Revision: https://secure.phabricator.com/D16752