vecu: enable stdio output

[rumpelsepp]

In order to enable testing in the CI for all protocols, we need a solution to be independent from OS specific stuff. Thus, let's create a stdio interface for the vecu and some kind of config were the wire protocol can be specified. I imagine some kind of DoIP over stdio, or CAN over stdio. This can be used to test all all kind of protocols (consequently the gallia.transport code) in the CI without relying on a properly setup virtual CAN bus.