feature: @DgsData should be @Repeatable

https://netflix.github.io/dgs/datafetching/#multiple-dgsdata-annotations-via-dgsdatalist

```java
@DgsData.List({
    @DgsData(parentType = "Query", field = "movies"),
    @DgsData(parentType = "Query", field = "shows")
})
```

couldn't `@DgsData` have [`@Repeatable`](https://docs.oracle.com/javase/tutorial/java/annotations/repeating.html)?
