further qualify pyodbc setinputsizes types for long stirngs

further qualify pyodbc setinputsizes types for long stirngs

Fixed regression caused by SQL Server pyodbc change :ticket:`8177` where we
now use ``setinputsizes()`` by default; for VARCHAR, this fails if the
character size is greater than 4000 (or 2000, depending on data) characters
as the incoming datatype is NVARCHAR, which has a limit of 4000 characters,
despite the fact that VARCHAR can handle unlimited characters. Additional
pyodbc-specific typing information is now passed to ``setinputsizes()``
when the datatype's size is > 2000 characters. The change is also applied
to the :class:`.JSON` type which was also impacted by this issue for large
JSON serializations.

Fixes: #8661
Change-Id: I07fa873e95dbd2c94f3d286e93e8b3229c3a9807