fix: Remove external control state

The external control state is deprecated and usage is currently being removed from gt-gen-core. Therefore, removing the declaration from mantle_api as well. It was meant to be used for the internal state of ADAS/AD functions. In the future this can be replaced by OSI::VehicleAutomatedDrivingFunction as part of OSI::TrafficUpdate, if needed. Currently OSC XML doesn't offer a condition to check the internal state of entities, so it doesn't make sense to add it now to the mantle_api.

Signed-off-by: Andreas Rauschert andreas.rb.rauschert@bmw.de