I think this is more of an issue rather than a feature request. Actually something that could've been implemented with #4556, but I didn't notice it at the time, so here we are.

Observed behaviour

Ships in atmosphere seem to preserve their angular momentum. Not okay IMO.
Demo: https://youtu.be/mCXzPTO0fLY (ships shouldn't rotate like that on the ground either, but that's another thing)

Expected behaviour

Ships should suffer angular drag, slowing their rotation down over time.

Steps to reproduce

1- Fly to/Start from a planet with an atmosphere.
2- Make sure you are in manual control and bring your speed as close to 0 as possible. (In order to ignore other atmospheric effects)
3- Turn off "Rotation Damping".
4- Press a rotation button (pitch, yaw, roll; anything) and watch the ship spin to eternity.