REST API (+nicocli) should support all internal operations

[kfelternv]

Goal

Track the original v2.0 REST API and nicocli parity work for admin operations that previously required carbide admin-cli.

The v2.1 follow-up REST/nicocli parity items have been split into #2852.

Scope

• Add REST API support for state-changing admin ops: power, bmc-reset, dpu-reprovision, health-override (Add REST API support for state-changing admin ops: power, bmc-reset, dpu-reprovision, health-override #2218).
• Add REST API endpoint for site-wide BMC credential setup (Add REST API endpoint for site-wide BMC credential setup #2219).

Follow-up

• Track the remaining post-audit REST API, nicocli, and documentation parity work in NICo CLI 2.1 follow-up REST parity #2852.