compiler: report error when trait object type param reference self Fixes #139082. Emits an error when `Self` is found in the projection bounds of a trait object. In type aliases, `Self` has no meaning, so `type A = &'static dyn B` where `trait B = Fn() -> Self` will expands to `type A = &'static Fn() -> Self` which is illegal, causing the region solver to bail out when hitting the uninferred Self. r? ````@compiler-errors```` ````@fee1-dead````