UnnecessaryModifier misses the opportunity to remove redundant modifiers from nested annotations, enums

`UnnecessaryModifier` misses the opportunity to remove redundant modifiers from nested annotations, enums

e.g.

```java
public interface Parent {
  public static abstract @interface MyAnnotation {}

  public static enum MyEnum {}
}
```

and

```java
public @interface Parent {
  public static abstract @interface MyAnnotation {}

  public static enum MyEnum {}
}
```