[display] range of field access hovers

When hovering over `Std`, only that token is part of the hover range. However, when hovering over `int`, the entire `Std.int` is highlighted.

This has an unfortunate consequence: When you move left-to-right, the hover switches from `Std` to `int` as expected:


However, moving in the other direction, nothing happens, as `Std` is already part of the current hover's range - if you want the docs on `Std`, you need to awkwardly "cancel" the current hover first:


I think it would be best if the range only included the actual field name, not the previous path part(s) as well. That seems to be what other languages like TS do.

____

```haxe
class Main {
static function main() {
var i = Std.int(0);
}
}
```