Check start time when deciding to include recurring event overrides
Check start time when deciding to include recurring event overrides

Summary: We were previously checking the UID on recurring event overrides to determine whether to include the 'inflated' version of an event or not. This worked because Google override UIDs are stored in the form "originaluid_DATETIME". However, EAS overrides have completely unique UIDs, so this patch changes the logic to check the time directly rather than making too-clever assumptions about the UID format.

Test Plan: Ensure unit tests still pass; also tested against a live EAS calendar with expand_recurring=True.

Reviewers: kav-ya

Differential Revision: https://phab.nylas.com/D1813

closeio/nylas,gale320/sync-engine,ErinCall/sync-engine,nylas/sync-engine,gale320/sync-engine,ErinCall/sync-engine,nylas/sync-engine,gale320/sync-engine,nylas/sync-engine,closeio/nylas,jobscore/sync-engine,Eagles2F/sync-engine,gale320/sync-engine,ErinCall/sync-engine,Eagles2F/sync-engine,jobscore/sync-engine,ErinCall/sync-engine,Eagles2F/sync-engine,closeio/nylas,closeio/nylas,Eagles2F/sync-engine,ErinCall/sync-engine,nylas/sync-engine,jobscore/sync-engine,jobscore/sync-engine,Eagles2F/sync-engine,gale320/sync-engine