2021-06-21

Merge #9346

9346: Refactor / clean up hir_ty tests r=flodiebold a=flodiebold

Notable changes:
 - unify `check_types` and `check_mismatches` into `check`, which supports both kinds of annotations (`check_types` still exists because I didn't want to change all the annotations, but uses the same implementation)
 - because of that, `check_types` now fails on any type mismatches; also annotations always have to hit the exact range
 - there's also `check_no_mismatches` for when we explicitly just want to check that there are no type mismatches without giving any annotations (`check` will fail without annotations)
 - test annotations can now be overlapping (they point to the nearest line that has actual code in that range):
```
// ^^^^ annotation
//    ^^^^^^^^^ another annotation
```

Co-authored-by: Florian Diebold <[email protected]>