scripts: twister: update twister to support QEMU platforms with sysbuild

Update twister to support running QEMU platforms with sysbuild, by parsing
domains.yaml and executing the "run" target of the default application.
This will allow twister to test QEMU targets with sysbuild. It is assumed
that QEMU targets will add any external images they need in the build
phase

Signed-off-by: Daniel DeGrasse <daniel.degrasse@nxp.com>