[3.13] gh-120221: Support KeyboardInterrupt in asyncio REPL (GH-123795) (#123799)

This switches the main pyrepl event loop to always be non-blocking so that it
can listen to incoming interruptions from other threads.

This also resolves invalid display of exceptions from other threads
(gh-123178).

This also fixes freezes with pasting and an active input hook.
(cherry picked from commit 033510e11dff742d9626b9fd895925ac77f566f1)

Co-authored-by: Łukasz Langa <lukasz@langa.pl>