CLN GH23123 Move SparseArray to arrays
- [X] closes #23123 
- [X] tests added / passed
- [X] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Importing `SparseArray` from the `Arrays` folder was causing circular import paths with the `__init__.py`, so I had to empty it and fix every other file that imported from `pandas.core.arrays`