Respect parenthesized generators in has_own_parentheses

[charliermarsh]

Summary

When analyzing:

if "root" not in (
    long_tree_name_tree.split("/")[0]
    for long_tree_name_tree in really_really_long_variable_name
):
    msg = "Could not find root. Please try a different forest."
    raise ValueError(msg)

We missed that the generator expression is parenthesized, because the parentheses are part of the generator -- so is_expression_parenthesized returns False. We needed to take into account that generators and tuples may or may not be parenthesized when determining whether we can omit parentheses while splitting an expression.

Closes #8090.

Test Plan

No changes in similarity.

Before:

project	similarity index	total files	changed files
cpython	0.75803	1799	1647
django	0.99983	2772	34
home-assistant	0.99953	10596	186
poetry	0.99891	317	17
transformers	0.99966	2657	330
twine	1.00000	33	0
typeshed	0.99978	3669	20
warehouse	0.99977	654	13
zulip	0.99970	1459	22

After:

project	similarity index	total files	changed files
cpython	0.75803	1799	1647
django	0.99983	2772	34
home-assistant	0.99953	10596	186
poetry	0.99891	317	17
transformers	0.99966	2657	330
twine	1.00000	33	0
typeshed	0.99978	3669	20
warehouse	0.99977	654	13
zulip	0.99970	1459	22

[charliermarsh]

An empty tuple has to be parenthesized. Otherwise, it... can't exist?

[charliermarsh]

I think this was a typo, but please correct me if I'm wrong.