Convenience method to get feature matrix orbit rank, and raise error for incorrect data items

[lbluque]

Summary

• Implemented convenience StructureWrangler.get_feature_matrix_orbit_rank to get rank of submatrices corresponding to a given orbit.
• Raise value error in StructureWrangler.append_data_items if an item is missing properties already included.

TODO (if any)

• Would be better to also make sure not additional properties are being included in appended items....

Checklist

• Code is in the standard Python style.
  Run pycodestyle and flake8
  on your local machine.
• Docstrings have been added in the Google docstring format.
  Run pydocstyle on your code.
• Tests have been added for any new functionality or bug fixes.
• All existing tests pass.