asdict use deep copy to dataclass instances

[Itayazolay]

BPO	44695
Nosy	@ericvsmith, @Itayazolay, @bentheiii, @akulakov
Superseder	bpo-43905: dataclasses.astuple (and .asdict) do deepcopy on all fields

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2021-11-28.19:17:43.451>
created_at = <Date 2021-07-21.11:29:22.227>
labels = ['type-bug', '3.8', '3.9', '3.10', '3.11', '3.7', 'library']
title = 'asdict use deep copy to dataclass instances'
updated_at = <Date 2021-11-28.19:17:43.448>
user = 'https://github.com/Itayazolay'

bugs.python.org fields:

activity = <Date 2021-11-28.19:17:43.448>
actor = 'andrei.avk'
assignee = 'none'
closed = True
closed_date = <Date 2021-11-28.19:17:43.451>
closer = 'andrei.avk'
components = ['Library (Lib)']
creation = <Date 2021-07-21.11:29:22.227>
creator = 'Itayazolay'
dependencies = []
files = []
hgrepos = []
issue_num = 44695
keywords = []
message_count = 2.0
messages = ['397938', '407220']
nosy_count = 4.0
nosy_names = ['eric.smith', 'Itayazolay', 'avrahami.ben', 'andrei.avk']
pr_nums = []
priority = 'normal'
resolution = 'duplicate'
stage = 'resolved'
status = 'closed'
superseder = '43905'
type = 'behavior'
url = 'https://bugs.python.org/issue44695'
versions = ['Python 3.7', 'Python 3.8', 'Python 3.9', 'Python 3.10', 'Python 3.11']

[Itayazolay]

Hi,
I noticed that 'asdict' use 'deepcopy' on all fields of the dataclass recursively.
I believe this behavior can become optional with an argument, and shouldn't be decided for the user as the deepcopy takes significant amount of cpu and can have unexpected consequences on memory.

I don't mind taking this PR if you agree.
Thanks

[akulakov]

Duplicate of https://bugs.python.org/issue43905