Provide a C API for introspectable frames for Cython and similar tools

GitHub fields:

assignee = 'https://github.com/markshannon'
closed_at = None
created_at = <Date 2021-11-26.16:41:33.564>
labels = ['type-feature', '3.11']
title = 'Provide a C API for introspectable frames for Cython and similar tools'
updated_at = <Date 2021-11-29.18:07:27.316>
user = 'https://github.com/markshannon'

bugs.python.org fields:

activity = <Date 2021-11-29.18:07:27.316>
actor = 'da-woods'
assignee = 'Mark.Shannon'
closed = False
closed_date = None
closer = None
components = []
creation = <Date 2021-11-26.16:41:33.564>
creator = 'Mark.Shannon'
dependencies = []
files = []
hgrepos = []
issue_num = 45905
keywords = []
message_count = 1.0
messages = ['407069']
nosy_count = 2.0
nosy_names = ['Mark.Shannon', 'da-woods']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue45905'
versions = ['Python 3.11']