df.rename works with 'mapper' and 'axis' params

[k3vob]

DataFrame.rename() will now change column names if mapper and axis=1 are provided as parameters, and axis names of mapper and axis=0 are provided

What do these changes do?

Related issue number

Resolves #1056

• passes flake8 modin
• passes black --check modin
• tests added and passing

[devin-petersohn]

Thanks @KevOBrien! A couple of comments:

• With the axis argument we should use the utility self._get_axis_number(axis). If we don't, it will only allow axis=1 or axis=0 and not allow axis="columns", etc. Then we can only check axis=0 or axis=1.
• We should also add a test to modin/pandas/test/test_dataframe.py to make sure we don't regress on this in the future.

[devin-petersohn]

I went ahead and fixed the comments I made