Re: [libvirt] [qemu PATCH v2] docs/interop: add "firmware.json"

Add a schema that describes the different uses and properties of virtual machine firmware. Each firmware executable installed on a host system should come with at least one JSON file that conforms to this schema. Each file informs the management applications about - the firmware's properties and one possible use case / feature set, - configuration bits that are required to run the firmware binary. In addition, define rules for management apps for picking the highest priority firmware JSON file when multiple such files match the search criteria.