feat(om2): add native histograms to OpenMetrics2.0 (#2634)

* feat(om2): add native histograms to OpenMetrics2.0

Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>
Signed-off-by: George Krajcsovits <krajorama@users.noreply.github.com>
Co-authored-by: Bartlomiej Plotka <bwplotka@gmail.com>
Co-authored-by: David Ashpole <dashpole@google.com>

Author: 3 people