[BUG] Should cudf.to_datetime(dayfirst=True) raise NotImplementedError?

[mroeschke]

Describe the bug
Should cudf.to_datetime(dayfirst=True) raise NotImplementedError?

Steps/Code to reproduce bug

In [6]: cudf.to_datetime(["10-02-2014"], dayfirst=True)
Out[6]: DatetimeIndex(['2014-10-02'], dtype='datetime64[ns]')

Expected behavior

In [6]: cudf.to_datetime(["10-02-2014"], dayfirst=True)
Out[6]: DatetimeIndex(['2014-02-10'], dtype='datetime64[ns]')

In DatetimeIndex.__init__, this specifically raises a NotImplementedError

        if dayfirst is not False:
            raise NotImplementedError("dayfirst == True is not yet supported")

Environment overview (please complete the following information)

• Environment location: Bare-metal
• Method of cuDF install: conda
  • If method of install is [Docker], provide docker pull & docker run commands used

Environment details
Please run and paste the output of the cudf/print_env.sh script here, to gather any other relevant environment details

Additional context
Add any other context about the problem here.