o.a.archive.engine: Check for invalid time stamps

This includes a workaround for VType bug #209 where out of range nanoseconds
would be reported as 'valid' yet cause a RuntimeException when fetching
the Timestamp.

The fix should show the affected channel name combined with the VType exception.
In the future, as VType.Time.isTimeValid() gets updated, it would show the invalid time stamp as such.