Support for @Attribute in annotated services

[ikhoon]

It would be good to support @Attribute annotation to declaratively inject the attributes in ServiceRequestContext.attr(key) into annotated services.

class MyService {

  @Get("/")
  public String hello(@Attribute("myAttribute") String myAttribute, ...) {
     ...
  }

}

[ikhoon]

Oops... it should be created in the Armeria repo. 😅