Fix DEBUG output for atomic group #106510
Description
It missed my attention that DEBUG output is not specialized for atomic groups (added in #34627). For example:
>>> re.compile('(?>ab?)', re.DEBUG)
ATOMIC_GROUP [(LITERAL, 97), (MAX_REPEAT, (0, 1, [(LITERAL, 98)]))]
...
The correct output should show the decoded structure of the subpattern:
>>> re.compile('(?>ab?)', re.DEBUG)
ATOMIC_GROUP
LITERAL 97
MAX_REPEAT 0 1
LITERAL 98
...