Fix default EBSD.detector attribute shape when detector is not passed upon initialization

[hakonanes]

Description of the change

Fix default EBSD.detector attribute shape when detector is not passed upon initialization.

Progress of the PR

• [n/a] Docstrings for all functions
• Unit tests with pytest for all lines
• Clean code style by running black via pre-commit

Minimal example of the bug fix or new feature

>>> import numpy as np
>>> import kikuchipy as kp
>>> s = kp.signals.EBSD(np.ones((1, 2, 3, 4))
>>> s.detector.shape
(3, 4)  # (4, 3) before this fix (ouch!)

For reviewers

• The PR title is short, concise, and will make sense 1 year later.
• New functions are imported in corresponding __init__.py.
• New features, API changes, and deprecations are mentioned in the unreleased
  section in CHANGELOG.rst.
• New contributors are added to release.py, .zenodo.json and
  .all-contributorsrc with the table regenerated.