Check MAVSDK server latency

[elpiel]

Check what is the request-response time for the MAVSDK server which underneath uses the MAVLINK protocol to send and receive messages.

This will help us determine if it's reliable for Proof of concept project regarding flying/controlling drones.

[elpiel]

There is still a need to check the latency of the MAVSDK server which is introduced by the added layer.

I've had a quick chat with @julianoes from the MAVLink community and he mentioned that the MAVSDK server has not been profiled, but it should be possible to get to 200 Hz with a release build on a Raspberry Pi 3.

This, however, is not backed by any data and the need for looking into this issue is with a higher priority.

[julianoes]

Caveat, so my assumption is that the MAVSDK library can handle it. I have no idea how the gRPC server part would handle it.