argparse: support options similar to find's -exec

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2021-02-08.20:40:56.769>
labels = ['type-feature', 'library', '3.10']
title = "argparse: support options similar to find's -exec"
updated_at = <Date 2021-02-08.20:44:09.515>
user = 'https://github.com/pkkm'

bugs.python.org fields:

activity = <Date 2021-02-08.20:44:09.515>
actor = 'zach.ware'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2021-02-08.20:40:56.769>
creator = 'pkkm'
dependencies = []
files = []
hgrepos = []
issue_num = 43169
keywords = []
message_count = 1.0
messages = ['386662']
nosy_count = 3.0
nosy_names = ['rhettinger', 'paul.j3', 'pkkm']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue43169'
versions = ['Python 3.10']