Create testing library to mirror pandas

[ajpotts]

Create a testing library to mirror pandas: https://github.com/pandas-dev/pandas/blob/main/pandas/_testing/asserters.py

Include assert_frame_equal, assert_index_equal, and assert_series_equal: https://pandas.pydata.org/docs/reference/api/pandas.testing.assert_frame_equal.html https://pandas.pydata.org/docs/reference/api/pandas.testing.assert_index_equal.html https://pandas.pydata.org/docs/reference/api/pandas.testing.assert_series_equal.html