Rollup merge of #83519 - oli-obk:assign_shrink_your_normal_code, r=pnkfelix

Rollup merge of #83519 - oli-obk:assign_shrink_your_normal_code, r=pnkfelix

Implement a lint that highlights all moves larger than a configured limit

Tracking issue: #83518
[MCP 420](https://github.com/rust-lang/compiler-team/issues/420) still ~blazing~ in progress

r? ```@pnkfelix```

The main open issue I see with this minimal impl of the feature is that the lint is immediately "stable" (so it can be named on stable), even if it is never executed on stable. I don't think we have the concept of unstable lint names or hiding lint names without an active feature gate, so that would be a bigger change.