When importing from another system into phabricator it's
reasonable to want to line up as much information as possible. For
example mapping priority names or creating custom fields. This commit
allows IDs to be explicitly set for applications that normally just
increment (so ticket 123 in the foreign system is ticket 123 in
maniphest) and set timestamps for transaction (so a search for 'that
thing from 8 years ago' still works instead of everything happening at
import time.
The ability to control timestamps would also presumable be useful for
settings up test scenarios for ETL or other features.
This is based on work done by the Blender project for their migration.
lint cleanup