[display] expected name for hover on enum arguments in patterns

Hovering over a function argument at call-site reports an expected name, which allows showing this "for argument" info:


It would be nice if the same info was provided in patterns as well - right now the JSON only includes the expected type, but no name.


```haxe
class Main {
static function main() {
var f:Foo;
switch (f) {
case Bar(a):
}
}
}

enum Foo {
Bar(foo:Int);
}
```