clinic: add option to pass module object to converter function

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2020-11-19.11:40:44.395>
labels = ['type-feature', 'expert-argument-clinic', '3.10']
title = 'clinic: add option to pass module object to converter function'
updated_at = <Date 2020-11-19.11:40:44.395>
user = 'https://github.com/tiran'

bugs.python.org fields:

activity = <Date 2020-11-19.11:40:44.395>
actor = 'christian.heimes'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Argument Clinic']
creation = <Date 2020-11-19.11:40:44.395>
creator = 'christian.heimes'
dependencies = []
files = []
hgrepos = []
issue_num = 42404
keywords = []
message_count = 1.0
messages = ['381406']
nosy_count = 4.0
nosy_names = ['vstinner', 'larry', 'christian.heimes', 'corona10']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue42404'
versions = ['Python 3.10']