Add new deviceinfo configuration supportsRebootToRecovery for reboot to recovery support

The Great Wizard Azkalirequested to merge
personal/azkali/supports-reboot-to-recovery into main

Adds the supportsRebootToRecovery capability key, defaulting to false in the halium config. Devices that expose a recovery target set it to true to advertise the capability.

Lomiri reads it (value-checked, ANDed with a user opt-in GSettings key) to show the "Restart to Recovery" entry in the power dialog. Companion to lomiri !160.

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