call setinputsizes for cx_Oracle.DATETIME

call setinputsizes for cx_Oracle.DATETIME

Restored adding cx_Oracle.DATETIME to the setinputsizes() call when a
SQLAlchemy :class:`.Date`, :class:`.DateTime` or :class:`.Time` datatype is
used, so that in the case where a bound parameter is passed as NULL
in some complex queries (in particular this happens with some lazy load
situations), the type is still present.  This was removed
in the 1.2 series for arbitrary reasons.

Also adds a suite test for this generic situation.

What's not clear is that do we really need setinputsizes() for all
datatypes if we are supporting NULL in bound parameters.

Fixes: #4886
Change-Id: If99215c31861f9ea6f60a30d47f2f320adc4797f