R1:c5efa3ecb5d5

Swap "Description" and "Invitees / Details" on Calendar event views

Summary:
Ref T11326. This reorders sections:

- Description (if present)
- Recurring event series info (if recurring)
- Invitees (this also has custom stuff, if it exists)

Test Plan: Viewed some events, saw more sensible order.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T11326

Differential Revision: https://secure.phabricator.com/D16671