Use new repo ref syntax and lockfile
This supersedes !33 (closed) and solves a part of https://git.kontron-electronics.de/sw/ked/plan/plan-ked-bsp/-/issues/1323.
Edited by Frieder Schrempf
This supersedes !33 (closed) and solves a part of https://git.kontron-electronics.de/sw/ked/plan/plan-ked-bsp/-/issues/1323.