Java: `Array.getPackage()` (and `Array.getQualifiedName()`) cannot be used

Trying to use `Array.getPackage()` or any predicate depending on it, such as `Array.getQualifiedName()`, causes a compilation error:
```
Expr::ExprParent incompatible with Type::Array in context
```

The underlying problem seems to be that `RefType.getPackage()` only considers classes and interfaces, but not arrays. Maybe for arrays it should be compilable but simply have no result (should be documented in `getPackage()` and `getQualifiedName()` for `RefType` and `Array` then; maybe for other predicates as well)?

Relates to #5320