[receiver/vcenter] Adds Datacenter metrics

[BominRahmani]

Description:

The following PR introduces multiple different metrics at a datacenter level. It takes advantage of processing thats already done at the cluster, host, vm, and datastore level in order to aggregate datacenter level metrics.

- vcenter.datacenter.cluster.count                 status={red/green/yellow, gray}
- vcenter.datacenter.vm.count                      status={red/green/yellow, gray} power_state={on/off/suspended}
- vcenter.datacenter.datastore.count               status={red/green/yellow, gray}
- vcenter.datacenter.host.count                    status={red/green/yellow, gray} power_state={on/off/standby/unknown}
- vcenter.datacenter.disk.space                    disk_state={used/available}
- vcenter.datacenter.cpu.limit
- vcenter.datacenter.memory.limit

Link to tracking Issue: #33607

Testing:
Tested against a live environment to make sure all values matched up.
Golden testing files have been updated.

Documentation:
All documentation was generated through mdatagen

[StefanKurek]

One small comment needs to be removed, but otherwise looks good