bpo-41818: Add termios.tcgetwinsize(), termios.tcsetwinsize(). (GH-23686)

* Add termios.tcgetwinsize(), termios.tcsetwinsize(). Update docs.
* Add TIOCGSIZE support to termios.tcgetwinsize()
* Add TIOCSSIZE support to termios.tcsetwinsize()

Authored-by: Soumendra Ganguly <soumendraganguly@gmail.com>

* termios.tcgetwinsize() and termios.tcsetwinsize() should return/accept two-item tuples instead of lists.
* Refactor tcsetwinsize to share common code and accept any two item sequence, with overflow checking.

Co-authored-by: Gregory P. Smith <greg@krypto.org> [Google]