export: Add support for Info, Stateset and gaugehistogram, metrics (new OM metric types).

[bwplotka]

Prometheus supports OM metric types (passed in metadata) since 2018. From a quick glance export returns error when OM is used with new types, which is emits debug log message.

AC:

• Export supports Info, Stateset and gaugehistogram (?) metric types

Alternatively we could instrument that error with the metric to know the scale of the problem.

[dcardellino24]

is there any update on this? Would like to see my metrics (StateSet, exposed by kube-state-metrics) in Google Metrics Explorer.