Deprecate unused EBSD metadata, remove EBSD.rebin() overriding HyperSpy

[hakonanes]

Description of the change

• Add deprecation warnings to EBSD methods related to metadata, since the metadata is mostly unused internally and should be removed in v0.6
• Remove the EBSD.rebin() overriding HyperSpy's Signal2D.rebin(), because it is unnecessary when the custom metadata is removed, and potentially breaking when the HyperSpy rebin() API changes (which it will in v1.7.0)

Progress of the PR

• 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

No external changes to EBSD.rebin() are made in this PR, and deprecation warnings are added

>>> import kikuchipy as kp
>>> s = kp.data.nickel_ebsd_large()
>>> s
<EBSD, title: patterns Scan 1, dimensions: (75, 55|60, 60)>
>>> s2 = s.rebin(scale=(1, 1, 2, 2))
<EBSD, title: patterns Scan 1, dimensions: (75, 55|30, 30)>
>>> s.set_experimental_parameters(xpc=1)
/home/hakon/kode/kikuchipy/kikuchipy/signals/ebsd.py:165: VisibleDeprecationWarning: Function `set_experimental_parameters()` is deprecated and will be removed in version 0.6.
  def set_experimental_parameters(
>>> s.set_phase_parameters(number=2)
/home/hakon/kode/kikuchipy/kikuchipy/signals/ebsd.py:296: VisibleDeprecationWarning: Function `set_phase_parameters()` is deprecated and will be removed in version 0.6.
  def set_phase_parameters(

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 doc/changelog.rst.
• New contributors are added to .all-contributorsrc and the table is regenerated.