R1:8e8818783599

Allow filtering of "date" custom fields

Summary: Ref T4663. Ref T4659. Allows "date" fields to be filtered with range parameters.

Test Plan:
- Added a custom "date" field with "search".
- Populated some values.
- Searched for dates using new range filters.
- Combined date search with other searches.
- Ran other searches independently.
- Inspected the generated queries.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: shadowhand, epriestley

Maniphest Tasks: T4659, T4663

Differential…