Auto merge of #32780 - soltanmm:consider-the-following, r=nikomatsakis

Replace consider_unification_despite_ambiguity with new obligation variant

Is work towards #32730. Addresses part one of #32286. Addresses #24210 and #26046 to some degree.

r? @nikomatsakis

src/librustdoc/clean/mod.rs

@@ -849,6 +849,7 @@ impl<'a> Clean<WherePredicate> for ty::Predicate<'a> {
             Predicate::Projection(ref pred) => pred.clean(cx),
             Predicate::WellFormed(_) => panic!("not user writable"),
             Predicate::ObjectSafe(_) => panic!("not user writable"),
+            Predicate::ClosureKind(..) => panic!("not user writable"),
         }
     }
 }