Generate vectorcall code to parse arguments using Argument Clinic

GitHub fields:

assignee = 'https://github.com/corona10'
closed_at = None
created_at = <Date 2021-03-09.11:34:23.944>
labels = ['expert-C-API', '3.10']
title = 'Generate vectorcall code to parse arguments using Argument Clinic'
updated_at = <Date 2022-03-06.09:38:05.594>
user = 'https://github.com/vstinner'

bugs.python.org fields:

activity = <Date 2022-03-06.09:38:05.594>
actor = 'kumaraditya'
assignee = 'corona10'
closed = False
closed_date = None
closer = None
components = ['C API']
creation = <Date 2021-03-09.11:34:23.944>
creator = 'vstinner'
dependencies = []
files = []
hgrepos = []
issue_num = 43447
keywords = []
message_count = 2.0
messages = ['388354', '389214']
nosy_count = 5.0
nosy_names = ['vstinner', 'serhiy.storchaka', 'corona10', 'erlendaasland', 'kumaraditya']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = None
url = 'https://bugs.python.org/issue43447'
versions = ['Python 3.10']