Update match branches

This updates all places where match branches check on StatementKind or UseContext.
This doesn't properly implement them, but adds TODOs where they are, and also adds some best
guesses to what they should be in some cases.

compiler/rustc_mir/src/transform/check_consts/validation.rs

@@ -808,6 +808,7 @@ impl Visitor<'tcx> for Validator<'mir, 'tcx> {
             | StatementKind::Retag { .. }
             | StatementKind::AscribeUserType(..)
             | StatementKind::Coverage(..)
+            | StatementKind::CopyNonOverlapping(..)
             | StatementKind::Nop => {}
         }
     }