Make concurrent.futures.Future usable outside of executors

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2021-10-04.19:31:22.097>
labels = ['type-feature', 'library', '3.11']
title = 'Make concurrent.futures.Future usable outside of executors'
updated_at = <Date 2021-10-08.21:22:50.931>
user = 'https://github.com/masklinn'

bugs.python.org fields:

activity = <Date 2021-10-08.21:22:50.931>
actor = 'terry.reedy'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2021-10-04.19:31:22.097>
creator = 'xmorel'
dependencies = []
files = []
hgrepos = []
issue_num = 45365
keywords = []
message_count = 1.0
messages = ['403181']
nosy_count = 1.0
nosy_names = ['xmorel']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'test needed'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue45365'
versions = ['Python 3.11']