`POINTER TO <function>` are now indexed in the codegen

…for less nosiy output

Previously when dealing with function pointer calls such as `fnPtr^()`
the resolver would only annotate the operator and any arguments. Some
codegen parts require an annotation on the whole call statement however
(which makes sense), as such this commit fixes the described issue.
Visuallized, assuming `fnPtr` points to a function returning a DINT:
```
fnPtr^();
^^^^^^^^ -> StatementAnnotation::Value { resulting_type: "DINT" }
```