Add a NativeHistogramBucketFactor parameter to the use of
`NewHistogramVec` in order to enable use of Prometheus Native
Histograms.
This will store automatically computed sparse buckets in CoreDNS.
If a compatible Prometeus requests native histograms this data will
returned instead of the static buckets.
The default factor of 1.05 should provide high quality resolution data.
Signed-off-by: SuperQ <superq@gmail.com>
0d6e113f90