Add getters for all SSLContext internal configuration

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2017-12-18.09:41:45.683>
labels = ['expert-SSL', 'type-feature', '3.8']
title = 'Add getters for all SSLContext internal configuration'
updated_at = <Date 2018-02-26.08:33:36.485>
user = 'https://github.com/njsmith'

bugs.python.org fields:

activity = <Date 2018-02-26.08:33:36.485>
actor = 'christian.heimes'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['SSL']
creation = <Date 2017-12-18.09:41:45.683>
creator = 'njs'
dependencies = []
files = []
hgrepos = []
issue_num = 32359
keywords = []
message_count = 8.0
messages = ['308533', '308535', '308536', '308541', '308547', '308548', '308594', '312890']
nosy_count = 5.0
nosy_names = ['janssen', 'christian.heimes', 'alex', 'njs', 'dstufft']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'needs patch'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue32359'
versions = ['Python 3.8']