Several instances of "first seen" and other fields assume an ordered input.

While doing some research on supporting fingerprint disassociation, I found many columns that assume that the event input stream is ordered by the event occurrence time. This assumption is incorrect for a lot of reasons, but mobile traffic is probably the most significant one.

This applies to at least the following columns (this list is not necessarily exhaustive):

- `Group.first_seen`
- `Group.last_seen`
- `Group.first_release`
- `Group.score`, since this is derived from `Group.last_seen`
- `GroupRelease.first_seen`
- `ReleaseEnvironment.first_seen`
- `TagValue.first_seen` (uses wall clock time, rather than event time)
- `TagValue.last_seen` (uses wall clock time, rather than event time)
- `GroupTagValue.first_seen` (uses wall clock time, rather than event time)
- `GroupTagValue.last_seen` (uses wall clock time, rather than event time)