Implement PyObject_GetMemoryView

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2020-03-03.15:18:37.776>
labels = ['expert-C-API', 'type-feature', '3.9']
title = 'Implement PyObject_GetMemoryView'
updated_at = <Date 2020-03-03.15:20:30.642>
user = 'https://github.com/nanjekyejoannah'

bugs.python.org fields:

activity = <Date 2020-03-03.15:20:30.642>
actor = 'vstinner'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['C API']
creation = <Date 2020-03-03.15:18:37.776>
creator = 'nanjekyejoannah'
dependencies = []
files = []
hgrepos = []
issue_num = 39836
keywords = []
message_count = 1.0
messages = ['363265']
nosy_count = 2.0
nosy_names = ['skrah', 'nanjekyejoannah']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue39836'
versions = ['Python 3.9']