[ide] dot completion doesn't work for modules that don't have a primary type

Mod.hx
```haxe
class Sub {}
```

Main.hx
```haxe
function main() {
Mod.|
}
```

Nothing is shown here, also `Mod` is not showing up in toplevel completion.

I assume this is tricky, because we don't really have a notion of module at expression level, but maybe `resolve_dot_path` can be taught to provide some completion?