Option to set startup directory in IDLE

GitHub fields:

assignee = 'https://github.com/terryjreedy'
closed_at = None
created_at = <Date 2016-11-22.17:54:11.977>
labels = ['3.8', 'expert-IDLE', 'type-feature', '3.7']
title = 'Option to set startup directory in IDLE'
updated_at = <Date 2020-03-13.00:37:26.033>
user = 'https://github.com/rhettinger'

bugs.python.org fields:

activity = <Date 2020-03-13.00:37:26.033>
actor = 'terry.reedy'
assignee = 'terry.reedy'
closed = False
closed_date = None
closer = None
components = ['IDLE']
creation = <Date 2016-11-22.17:54:11.977>
creator = 'rhettinger'
dependencies = []
files = []
hgrepos = []
issue_num = 28775
keywords = []
message_count = 8.0
messages = ['281494', '281554', '281645', '281807', '281823', '329974', '341653', '364059']
nosy_count = 4.0
nosy_names = ['rhettinger', 'terry.reedy', 'Nofar Schnider', 'anthonypjshaw']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'test needed'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue28775'
versions = ['Python 3.7', 'Python 3.8']