307cf692e5
**Rationale** A general `mjGAIN_AFFINE` actuator adds the term `force = (c + kp * length + kv * velocity) * ctrl`. The damper shortcut restricts it to `kv * velocity * ctrl` and sets the `ctrllimited` attribute to true. **API** ```xml <actuator> <damper ctrlrange="0 1" kv="1"/> </actuator> ``` * Required attributes: `ctrlrange` (>=0) * Optional attributes: `kv` (>=0) PiperOrigin-RevId: 455366866 Change-Id: I88773abbeccabb6442f215c9fc05e205df63f692