Initial tests of RARE/freeRtr backplane feature.
https://github.com/vixphy/freertr-backplane/tree/main/emulated
https://github.com/vixphy/freertr-backplane/tree/main/virtualized
http://sources.freertr.org/cfg/p4lang-rout211.tst
https://github.com/rare-freertr/freeRtr/blob/master/cfg/p4lang-rout211.tst