Limit CPCs the exporter exports

[andy-maier]

There are situations where not all CPCs managed by an HMC should be exported. Or where they should be exported by separate exporter instances for some reason.

This issue is to add support for limiting the CPCs for which metrics are exported, to a specific subset of the CPCs managed by the HMC that is being targeted.

[vmorris]

Hi, can this get some priority? I have a situation where I could utilize it, thanks.