Add fitting of a plane to projection centers

[hakonanes]

Description of the change

This PR adds the following functionality to EBSDDetector:

• fit_pc(): Fit a plane to selected projection centers (PCs) using either a projective or affine transformation, following the work of Winkelmann et al. (https://doi.org/10.3390/ma13122816). This functionality is adapted from Winkelmann's xcdskd package (https://github.com/wiai/xcdskd).
• extrapolate_pc(): Extrapolate a plane of PCs from a mean or single PC to a map of PCs, following the work of Singh et al. (https://doi.org/10.1107/S1600576717014200). This is used in EMsoft's FitOrientation program (no orientation correction, as they do, is currently implemented). This solves part of Orientation correction after dictionary indexing (and PC correction) before refinement #454.
• estimate_xtilt(): Estimate tilt about detector X axis which brings the detector normal parallel to the sample normal, assuming no other tilts. Also adapted from xcdskd.
• estimate_xtilt_ztilt(): Estimate tilts about detector X and Z axes which bring the detector normal parallel to the sample normal, assuming no other tilts. Also adapted from xcdskd.
• plot_pc(): Plot PCs either in three maps or scatter plots (PCx, PCy), (PCx, PCz), (PCz, PCy), or in a 3D scatter plot (PCx, PCz, PCy).

All methods are used in three examples added to the example gallery. They will also be used in tutorial notebooks coming in a follow-up PR.

Other changes/additions:

• Adds a kikuchipy.draw.plot_pattern_positions_in_map() convenience function to plot pattern positions (e.g. those we use for PC fitting) on a 2D map. Is used in an example, will be used in coming new tutorials.
• Refinement speed patterns/s is now a float (gave 0 patterns/s before because it was an integer).

Progress of the PR

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

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.