Add lint for comparing to empty slices instead of using .is_empty()

[Urcra]

Hey first time making a clippy lint

I added the implementation of the lint the len_zero since it shared a lot of the code, I would otherwise have to rewrite. Just tell me if the lint should use it's own file instead

changelog: Add lint for comparing to empty slices

Fixes #6217

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @flip1995 (or someone else) soon.

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[flip1995]

Thanks for your (almost perfect) first contribution and welcome to Clippy! <3

[Urcra]

Thanks for your (almost perfect) first contribution and welcome to Clippy! <3

Thanks, and thank you for the review

[flip1995]

@bors r+

Thanks!

[bors]

📌 Commit e3de544 has been approved by flip1995

[bors]

⌛ Testing commit e3de544 with merge e1a2845...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: flip1995
Pushing e1a2845 to master...