moveByVelocityZ in body frame

[meurissemax]

What feature are you suggesting?

Overview:

I experienced a small problem with function moveByVelocityBodyFrame (when used to move in X-Y plane): multiple calls, separated by a small amount of time (for example, the time to process and analyze an image) leads the UAV to move downwards gradually.

A small video illustrating this problem is available here: https://youtu.be/iiWdGzhMKqA

The use of moveByVelocityZ solved this problem, but unfortunately its associated moveByVelocityZBodyFrame does not exist, so I propose to add it.

Smaller Details:

The implementation would be (almost) exactly the same as the moveByVelocityBodyFrame added in #3169.

Usage: moveByVelocityZBodyFrameAsync(vx, vy, z, duration, drivetrain (optional), yaw_mode (optional), vehicle_name (optional)).

Nature of Request:

• Addition

Why would this feature be useful?

To be consistent in the methods proposed in the API for moving using velocity.

Indeed, the function moveByVelocity has its associated moveByVelocityBodyFrame. It is not the case for the function moveByVelocityZ.