Fixes wrong heading in MockGPSNode outgoing sensor_gps messages.
Fixes a null reference when gimbal_projection is disabled.
Changes GStreamer UDP port to 5601 (already changed in gisnav-docker version). Plan to eventually remove these duplicate test/assets configuration files in this repo and use the ones in gisnav-docker repo.
test/assets
configuration files in this repo and use the ones ingisnav-docker
repo.