gh-90092: Support multiple terminals in the curses module (GH-151748)

gh-90092: Support multiple terminals in the curses module (GH-151748)

Add the X/Open Curses SCREEN API for driving more than one terminal:
newterm() and set_term(), plus the ncurses extension new_prescr().

A new screen object wraps the C SCREEN.  It exposes the terminal's
standard window as screen.stdscr.  Each window keeps a reference to its
screen (like a subwindow does to its parent window), so the screen is
deleted automatically once it and all of its windows are unreferenced.

The ncurses use_screen()/use_window() locking helpers are exposed as
the screen.use() and window.use() methods.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>