[tlBMC/g3doc] Document Host State Management

Created documentation for the Host State Management module in `components/host_state.md`.
Details the PowerControl interface, PowerControlGpio implementation (GPIO-based state machine), and PowerControlInotify (file-based inotify monitoring).
Based on `host_state/host_state_collector.cc` and `host_state/power_control.cc`.

PiperOrigin-RevId: 931347793
Change-Id: Id3ff2147c210c643fd2ab5dd645c59469b932a2b
1 file changed