Improve __repr__ of TypeVar

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2022-03-19.17:19:22.518>
labels = ['type-feature', '3.11']
title = 'Improve __repr__ of TypeVar'
updated_at = <Date 2022-03-19.17:19:22.518>
user = 'https://github.com/ktbarrett'

bugs.python.org fields:

activity = <Date 2022-03-19.17:19:22.518>
actor = 'ktbarrett'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = []
creation = <Date 2022-03-19.17:19:22.518>
creator = 'ktbarrett'
dependencies = []
files = []
hgrepos = []
issue_num = 47068
keywords = []
message_count = 1.0
messages = ['415562']
nosy_count = 1.0
nosy_names = ['ktbarrett']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue47068'
versions = ['Python 3.11']