Auto merge of rust-lang#146069 - camsteffen:range-desugar-span, r=SparrowLii

Mark desugared range expression spans with DesugaringKind::RangeExpr

This is a prerequisite to removing `QPath::LangItem` (rust-lang#115178) because otherwise there would be no way to detect a range expression in the HIR.

There are some non-obvious Clippy changes so a Clippy team review would be good.

Author: bors