Idlelib: document or move delayed imports

GitHub fields:

assignee = 'https://github.com/terryjreedy'
closed_at = None
created_at = <Date 2016-08-30.01:54:22.618>
labels = ['expert-IDLE', 'type-feature', '3.10']
title = 'Idlelib: document or move delayed imports'
updated_at = <Date 2020-06-06.22:08:56.119>
user = 'https://github.com/terryjreedy'

bugs.python.org fields:

activity = <Date 2020-06-06.22:08:56.119>
actor = 'terry.reedy'
assignee = 'terry.reedy'
closed = False
closed_date = None
closer = None
components = ['IDLE']
creation = <Date 2016-08-30.01:54:22.618>
creator = 'terry.reedy'
dependencies = ['27891']
files = []
hgrepos = []
issue_num = 27892
keywords = []
message_count = 2.0
messages = ['273893', '273896']
nosy_count = 1.0
nosy_names = ['terry.reedy']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'needs patch'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue27892'
versions = ['Python 3.10']