Dasharo (coreboot + UEFI) support for PC Engines apus board

https://github.com/Dasharo/presentations/blob/main/dasharo_roadmap.md#new-dasharo-network-appliance-roadmap

Overview: https://docs.dasharo.com/variants/pc_engines/overview/
Previous release: https://docs.dasharo.com/variants/pc_engines/releases_uefi/