Merge pull request #3283 from dheaton-arm/implement-umulhi

Implement `Umulhi` for the interpreter

cranelift/codegen/meta/src/shared/instructions.rs

@@ -2454,8 +2454,7 @@ pub(crate) fn define(
         Unsigned integer multiplication, producing the high half of a
         double-length result.
 
-        Polymorphic over all scalar integer types, but does not support vector
-        types.
+        Polymorphic over all integer types (vector and scalar).
         "#,
             &formats.binary,
         )