fix: local items should not be completed in parent signature
fixes#11959
> We get a Bar completion for the following snippet which is wrong as the item is not visible in that position.
> ``` rust
> fn foo() -> $0 {
> struct Bar;
> }
> ```
I investigated the problem and found that the scope of the cursor offset, also `CompletionContext.scope` is the body of the function
7322a982f9