[Tracking Issue] Refactor lints in methods module

[TaKO8Ki]

This issue is linked with #6680.

I've refactored most of lints in methods module in #6826 and the PR became too large.
So, I'm going to refactor the rest of lints and move some functions to clippy_lints/src/utils/methods/ in a new PR.

This issue is a tracking issue for doing this to avoid opening a too large PR and split them into small PRs.

TODO

• refactor lints other than CHARS_NEXT_CMP and CHARS_LAST_CMP in Refactor: arrange lints in methods module #6826
• refactor CHARS_NEXT_CMP
• refactor CHARS_LAST_CMP
• Refactor: arrange lints in methods module #6826 (comment)
• move functions such as derefs_to_slice to clippy_lints/src/utils/methods/
  review comments
• Refactor: arrange lints in methods module #6826 (comment)
• Refactor: arrange lints in methods module #6826 (review)
• move checks that decide whether the lint is triggered to each module.
  review comment: Refactor: arrange lints in methods module #6826 (comment)

[TaKO8Ki]

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