bpo-433030: Add support of atomic grouping in regular expressions (GH-31982)

* Atomic grouping: (?>...).
* Possessive quantifiers: x++, x*+, x?+, x{m,n}+.
  Equivalent to (?>x+), (?>x*), (?>x?), (?>x{m,n}).

Co-authored-by: Jeffrey C. Jacobs <timehorse@users.sourceforge.net>
11 files changed