Expose BootOptions CRUD operations via SystemRegistry.
Expose BootOptions getter, add, update-enabled, and delete methods in the tlbmc SystemRegistry HAL to support Redfish out-of-band boot configuration.
Similar to BootNext, BootSourceOverrideTarget, and BootSourceOverrideEnabled, BootOptions maps Redfish system IDs ("system", "system1", "system2") to gbmc-settings backed persistent storage.
- Add GetBootOptions, GetBootOption, AddBootOption, UpdateBootOptionEnabled, and DeleteBootOption to the SystemRegistry interface.
- Implement methods in SystemRegistryImpl delegating to SettingsManager.
- Add corresponding mock methods in MockSystemRegistry.
- Add unit tests in system_registry_impl_test covering default empty state, add/get, duplicate and validation error handling, enable/disable updates, deletion, multi-host isolation, and invalid system ID handling.

Google-Bug-Id:539554519
PiperOrigin-RevId: 994521126
Change-Id: Ib85106bb84768801ab9a532648f209ed6ea7931b