unhelpful error position for @:generic+Constructible+new

*(extracted from a [forum question](https://community.haxe.org/t/generic-class-with-t-dynamic-referenced-for-type-possibly-instantiated/2480))*

```haxe
import haxe.Constraints.Constructible;

@:generic
class GenericBase Void>> {
public function new() {
new T();
}
}

function main() {
new GenericBase();
}
```

This will error `src/Main.hx:5: lines 5-7 : Dynamic has no field new`, but the position is pointing to `GenricBase.new` method which is unhelpful. We should probably add one of these "called from here" line for it, so the user knows what caused invalid @:generic instantiation. Or maybe we could error even before @:generic is instantiated, by not allowing `Dynamic` to pass `Constructible` constraint check.

Reproduce the example in src/Main.hx and inspect the compiler diagnostic for the @:generic Constructible instantiation. Trace where the error is reported versus where new GenericBase() triggers it. Done means the diagnostic identifies the instantiation or provides a useful “called from here” location, with the example covered by a regression check.

Written by the indexing model from the issue text.