See https://github.com/ankitects/anki/pull/900#issuecomment-758284016
- Leave tag names alone and add the collapsed and config columns to the tags table.
- Update The DB check code to preserve the collapse state of used tags.
- Add a simple test for clearing tags and their children
- use the TimestampSecs newtype instead of raw i64s
- use FixedOffset instead of a minutes_west offset
- check localOffset each time the timing is calculated, and set it
if it's stale - even for v1.
- check for and fix missing rollover when calculating timing
- stop explicitly passing localOffset in the sync/start call
