Add +REPORT_NDIFF option to pdb tests that use doctest

GitHub fields:

assignee = 'https://github.com/akulakov'
closed_at = None
created_at = <Date 2021-09-19.00:58:51.709>
labels = ['type-feature', 'tests', '3.11']
title = 'Add +REPORT_NDIFF option to pdb tests that use doctest'
updated_at = <Date 2021-09-24.20:06:44.223>
user = 'https://github.com/akulakov'

bugs.python.org fields:

activity = <Date 2021-09-24.20:06:44.223>
actor = 'terry.reedy'
assignee = 'andrei.avk'
closed = False
closed_date = None
closer = None
components = ['Tests']
creation = <Date 2021-09-19.00:58:51.709>
creator = 'andrei.avk'
dependencies = []
files = []
hgrepos = []
issue_num = 45240
keywords = ['patch']
message_count = 2.0
messages = ['402142', '402583']
nosy_count = 4.0
nosy_names = ['terry.reedy', 'lukasz.langa', 'kj', 'andrei.avk']
pr_nums = ['28453']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue45240'
versions = ['Python 3.11']