feat(lints): add unsigned_subtraction_gt_zero lint for comparisons against zero after subtraction

[AMS21]

changelog: new lint: [unsigned_subtraction_gt_zero] Lints comparisons of an unsigned integer subtraction against zero, like (a - b) > 0.

If a < b, a - b will panic in debug builds and wrap in release builds, making the effectively behave like a != b. This is likely unintended; a > b is clearer and avoids potential panics and wraparound.

Fixes #588

[rustbot]

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[github-actions]

Lintcheck changes for e452f1b

Lint	Added	Removed	Changed
clippy::unsigned_subtraction_gt_zero	1	0	0

This comment will be updated if you push new changes

[Alexendoo]

Opened https://rust-lang.zulipchat.com/#narrow/channel/257328-clippy/topic/FCP.20unsigned_subtraction_gt_zero/with/546064561

[rustbot]

This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.