CylinderSegment barycenter

[Alexboiboi]

Adresses #480

The CylinderSegment magnetization should maybe use this PR for the arrow start position (see #482)

Question: Should we cache the call for barycenter to avoid recalculation every time it is called (e.g. using @lru_cache)

import magpylib as magpy
import numpy as np

cs = magpy.magnet.CylinderSegment(
    magnetization=(100, 0, 0), dimension=(1, 2, 1, 85, 170), style_opacity=0.5
)

cs.rotate_from_angax([76 * i for i in range(0, 5)], "x", anchor=(0, 0, 5), start=0)

cs.show(
    markers=cs._barycenter.tolist(),
    style_marker_size=5,
    style_path_frames=1,
    backend="plotly",
)

[OrtnerMichael]

Looks good,

There is a minor docstring error which makes me realize that I did not review the property docstrings. I will fix this in a subsequent update.

"Output shape is matches position and orientation."