Cannot generate message definitions compatible with current low-can binding

When agl-service-can-low-level was reworked to switch to libappcontroller plugins for the message definitions, it seems that a corresponding change to low-level-can-generator to generate the message definition structure used for the plugins was missed.  For example, it seems not possible to regenerate e.g. examples/agl-vcar/agl-vcar-signals.cpp which was updated in commit 74e83bfd ("Cleanup examples, tests, configuration and plugins").