Host reboot for the host Component

[bburda]

Summary

Implement LifecycleProvider restart/shutdown for the host Component (the machine the gateway runs
on), so a Component-level reset reboots or shuts down the host.

Proposed solution

• Implement restart/force-restart/shutdown/force-shutdown for the host Component via a host control
  mechanism (for example systemd reboot/poweroff).
• Privileged, high-impact action: off by default, explicitly enabled in config, RBAC-gated, and
  advertised only when enabled.
• Remote host Components are handled by existing aggregation forwarding: the transition is
  forwarded to the peer gateway that owns the host.

Contributes coverage toward REQ_INTEROP_077-081 at the host/Component level.
Unit and integration tests, docs.