Support __le__ and __ge__ operators for CharSpan, TokenSpan

[BryanCutler]

If we don't want to support these, remove these from all_compare_operators test fixture

[frreiss]

Since we already have __lt__, __gt__, and __eq__ for these types, adding __le__ and __ge__ is both a good idea and easy to do. Adding the "good first issue" tag to this issue. @BryanCutler can you please elaborate on the additional work that needs to be done beyond adding __le__ and __ge__ to the CharSpan and CharSpanArray classes?

[BryanCutler]

Once implemented, the Pandas base tests can be enabled by removing the below lines from TestPandasComparisonOps._compare_other

        if op_name in ["__le__", "__ge__"]:
            pytest.skip("op not supported")