Should we support customization of the time zone?

[sleberknight]

Currently the ApplicationError factory methods will all create a new instance with createdAt and updatedAt using UTC as the time zone. The RecentErrorsHealthCheck does the same thing when creating the reference dates. For all our usage so far, this is fine since all our servers and databases are set to UTC. But there could be situations where this isn't true, and it might be nice to have a way to configure the time zone this library should use when creating new ApplicationError instances and in the health check. I didn't look to hard, so there might be other places where we instantiate ZonedDateTime instances.

A possible alternative is to switch all the ZonedDateTime fields and method arguments to use Instant instead, but that would have a rather large impact on our dozens of services that already use this library, in that we'd need to make a major version change, and then upgrade all the services (since they won't compile without changes).