Track if a where bound comes from a impl Trait desugar

With #93803 `impl Trait` function arguments get desugared to hidden
where bounds. However, Clippy needs to know if a bound was originally a
impl Trait or an actual bound. This adds a field to the
`WhereBoundPredicate` struct to keep track of this information during
HIR lowering.

compiler/rustc_ast_lowering/src/lib.rs

@@ -1298,6 +1298,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                             def_node_id,
                             &GenericParamKind::Type { default: None },
                             hir_bounds,
+                            hir::PredicateOrigin::ImplTrait,
                         ) {
                             in_band_ty_bounds.push(preds)
                         }