fix [`undocumented_unsafe_blocks`] FP with trait/impl items

[J-ZhengLi]

fixes: #11709 close: #12720

do-over of #11813 , I was trying to fix multiple problems at once thus making that PR hard to review, also hard to maintain after so many conflicts... So, here's a new one, should be a bit simpler to review the changes.

r? @Alexendoo if you don't mind?

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changelog: fix [undocumented_unsafe_blocks] FP with trait/impl items

[xFrednet]

Hey, this is a ping from triage. @Alexendoo can you give this PR a review? It's totally fine if you don't have the time right now, you can reassign the PR to a random team member using r? clippy.

@rustbot ready

[Alexendoo]

I believe https://github.com/rust-lang/rust-clippy/pull/12672#discussion_r1647561890 still applies here

[xFrednet]

Okay, then a ping to @J-ZhengLi, have you seen the referenced comment?

@rustbot author

[J-ZhengLi]

Okay, then a ping to @J-ZhengLi, have you seen the referenced comment?

@rustbot author

Ahh yes, sorry I have some time sensitive task for my job lately, is it ok if I left this PR hang for 2 more weeks? I should have more time at the end of August, so I can finally got back to clippy by then :D.

[xFrednet]

Yeah, no problem, IRL stuff comes first! :D