8072645: java.util.logging should use java.time to get more precise time stamps
Summary: j.u.logging uses j.t.Instant to store LogRecord time stamps. XMLFormatter format is updated to allow for a new optional <nanos> element containing a nano second adjustment. SimpleFormatter passes a ZonedDateTime object to String.format. LogRecord getMillis/setMillis are deprecated, replaced by getInstant/setInstant.
Reviewed-by: scolebourne, plevart, rriggs
Contributed-by: daniel.fuchs@oracle.com, peter.levart@gmail.com