Implement configurable position offsets.

[danzimmerman]

This PR adds the parameters offset_pos_to_dev and offset_pos_from_dev to bus.yml to allow user-defined offsets in the position feedback and commands. These default to zero if not specified.

One use case is remapping the sense of rotation and angle convention for a joint with an absolute angle encoder whose rotation direction cannot be reversed physically or electronically.

Assuming full-scale encoder count $n_{fs}$ and current count $n_{enc}$, mapping position feedback from the device, with offset_pos_from_dev = 2*pi, scale_pos_from_dev = -2*pi/n_fs:

$$\large \theta = 2\pi - \frac{2\pi}{n_{fs}}n_{enc}$$

Mapping commands to the device, with offset_pos_to_dev = n_fs, scale_pos_to_dev = -n_fs/(2*pi):

$$\large n_{enc} = n_{fs} - \frac{n_{fs}}{2\pi}\theta$$

This could also be useful for absolute position encoders that otherwise cannot be zeroed at a given physical position.

[danzimmerman]

I fixed the formatting with the pre-commit hook. Sorry I missed that at first.

[danzimmerman]

Also updated the CiA402 driver bus configuration docs to match.