to support annotation attributes override for @Service and @Reference

[dhchao11]

at some cases, i want to define a new annotation class that is annotated with @reference, and in the new class, i use AliasFor for attribute override, but it does not work. i want to pull a request and enhance this function.

the sample code is like this: i want to redefine the group name to n"dubbo"

`@Documented
@retention(RetentionPolicy.RUNTIME)
@target({ElementType.FIELD, ElementType.METHOD})
@reference
public @interface SelfDefineReference {

@AliasFor(annotation = Reference.class, attribute = "group")
String group() default "dubbo";

}`