System: expose vehicle type?

[Luc-Meunier]

Hi, I see that in mavsdk::System we can get the autopilot's type
https://mavsdk.mavlink.io/main/en/cpp/api_reference/classmavsdk_1_1_system.html#classmavsdk_1_1_system_1af3ded5464f6025f5d31955e100e15894

I also see that there is this getter in SystemImpl:
MAV_TYPE SystemImpl::get_vehicle_type()

So I was wondering if we could also expose the vehicle type in mavsdk::System.
It is really useful when dealing with different kinds of UAVs.

[julianoes]

I guess a string operator like you did for the Autopilot would be nice.

[Luc-Meunier]

OK then here is my PR #2559 to expose the vehicle type (https://mavlink.io/en/messages/common.html#MAV_TYPE) in the System class (https://mavsdk.mavlink.io/main/en/cpp/api_reference/classmavsdk_1_1_system.html)