Complete tests for EBSDSimulationGenerator

[hakonanes]

Description of the change

• Finish preliminary testing of kikuchipy.generators.EBSDSimulationGenerator. (More test cases might be added when finishing testing of other functionality not currently tested.)
• Improve calculation of Kikuchi band detector coordinates using numpy.tensordot
• Remove (for now) unnecessary reciprocal_lattice_point parameter when initializing a kikuchipy.simulations.GeometricalEBSDSimulation (phase with crystal structure, symmetry operations etc., hkl/Miller planes etc. are stored within the kikuchipy.simulations.features.KikuchiBand object)
• Add EBSDSimulationGenerator to API reference
• Set up intersphinx with orix, so that docstring references in kikuchipy to orix points directly to relevant elements in https://orix.readthedocs.io/en/stable/reference.html

Progress of the PR

• Docstrings for all functions
• Unit tests with pytest for all lines
• Clean style in as per black
• Expand EBSDSimulationGenerator property/method docstrings with examples and references.

For reviewers

• Check that the PR title is short, concise, and will make sense 1 year
  later.
• Check that new functions are imported in corresponding __init__.py.
• Check that new features, API changes, and deprecations are mentioned in
  the unreleased section in doc/changelog.rst.