8986: Add go to type definition for struct fields within struct r=matklad a=lf-
Example:
```rust
struct A;
struct B {
a/*<- cursor*/: A,
}
```
Go to type definition used to not work on this position. It now goes to
`A` as expected.
Co-authored-by: Jade <software@lfcode.ca>
b7414fa14a