Support for storage information in redfish plugin

## Feature Request

The current redfish plugins only supports thermal and power informations from the redfish standard.

### Proposal:

Adding support for the redfish's storage metrics

### Current behavior:

Only metrics for power, fans and thermals are gathered by telegraf

### Desired behavior:

Add storage metrics to existing thermals, fans and power. Maybe the possibility to enable or disable each of theses categories to fit any use case.

### Use case:

I would like this feature be able to monitor physical servers through their management interface (iLO for HPE or iDRAC for Dell, maybe others) to trigger alarms through my monitoring stack.
I know that i could use SNMP, but it's more work to implement, needing to specify the whole snmp structure that i want, and i'd rather not enable IPMI (which we don't really use) to avoid adding another open service.
Redfish being implemented as part of the existing web service of these management interfaces, it also doesn't require much configuration on the server side.

Begin by locating the existing Redfish plugin that gathers power, fan, and thermal metrics. Review its collection and configuration boundaries, then identify the Redfish storage data that should be exposed and whether each metric category needs independent enable/disable controls. Done means storage metrics are collected alongside the existing categories with the intended configuration behavior.

Written by the indexing model from the issue text.