Auto merge of #88175 - camsteffen:let-desugar-span, r=Manishearth

Add expansion to while desugar spans

In the same vein as #88163, this reverts a change in Clippy behavior as a result of #80357 (and reverts some `#[allow]`s): This changes `clippy::blocks_in_if_conditions` to not fire on `while` loops. Though we might actually want Clippy to lint those cases, we should introduce the change purposefully, with tests, and possibly under a different lint name.

The actual change here is to add a desugaring expansion to the spans when lowering a `while` loop.

r? `@Manishearth`

compiler/rustc_span/src/hygiene.rs

@@ -1101,6 +1101,7 @@ pub enum DesugaringKind {
     Await,
     ForLoop(ForLoopLoc),
     LetElse,
+    WhileLoop,
 }
 
 /// A location in the desugaring of a `for` loop
@@ -1122,6 +1123,7 @@ impl DesugaringKind {
             DesugaringKind::OpaqueTy => "`impl Trait`",
             DesugaringKind::ForLoop(_) => "`for` loop",
             DesugaringKind::LetElse => "`let...else`",
+            DesugaringKind::WhileLoop => "`while` loop",
         }
     }
 }