Expose SCTs on TLS connections

GitHub fields:

assignee = 'https://github.com/tiran'
closed_at = None
created_at = <Date 2017-05-31.12:21:52.625>
labels = ['expert-SSL', 'type-feature', '3.8']
title = 'Expose SCTs on TLS connections'
updated_at = <Date 2018-12-18.14:00:16.845>
user = 'https://github.com/alex'

bugs.python.org fields:

activity = <Date 2018-12-18.14:00:16.845>
actor = 'christian.heimes'
assignee = 'christian.heimes'
closed = False
closed_date = None
closer = None
components = ['SSL']
creation = <Date 2017-05-31.12:21:52.625>
creator = 'alex'
dependencies = []
files = []
hgrepos = []
issue_num = 30525
keywords = []
message_count = 3.0
messages = ['294838', '301471', '332060']
nosy_count = 4.0
nosy_names = ['janssen', 'christian.heimes', 'alex', 'dstufft']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'needs patch'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue30525'
versions = ['Python 3.8']