bpo-26806: add 30 to the recursion limit in IDLE's shell (GH-13944)

bpo-26806: add 30 to the recursion limit in IDLE's shell (GH-13944)

This is done to compensate for the extra stack frames added by
IDLE itself, which cause problems when setting the recursion limit
to low values.

This wraps sys.setrecursionlimit() and sys.getrecursionlimit()
as invisibly as possible.
(cherry picked from commit fcf1d003bf4f0100c9d0921ff3d70e1127ca1b71)

Co-authored-by: Tal Einat <taleinat+github@gmail.com>