Convert Cython extension class properties to decorator syntax part 1 of 4

[JoeSchiff]

"Showing 24 changed files with 907 additions and 843 deletions."
I doubt that you want this all in one PR, so I broke it up into more manageable chunks.

We currently use a legacy syntax for defining properties in an extension class which has been deprecated since ~2016:
https://cython.readthedocs.io/en/stable/src/userguide/extension_types.html#properties

Switching to the new syntax required moving the property docstrings. Previously, the docstring was placed on the line below the property keyword. However, using the new syntax there can not be anything between the decorator and the def statement, so the docstring was moved to below the def statement.

[WyattBlue]

Thank you