cmake: create domains.yaml

Support creation of domains.yaml to support
`west <build|flash|debug> --domain` when working with sysbuild multi
image.

Each Zephyr based image is added to list of domain that can be handled
by the Zephyr west extension commands.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>
3 files changed