Rollup merge of #156565 - aerooneqq:delegation-self-type-ice, r=petrochenkov

delegation: emit error when self type is not specified and accessed

This PR adds error reporting when we create error self type if it was not specified. In most of the tests there were other errors, so this delayed bug was not triggered, but there are cases like `reuse Default::default;` (rust-lang/rust#156388) which does not emit other errors and those delayed bugs are triggered.

Part of rust-lang/rust#118212. Fixes rust-lang/rust#156388.

r? @petrochenkov