Support application roles per endpoint

[rbygrave]

1. Create an app specific enum that implements Role

import io.avaje.jex.Role;

/**
 * Create an App specific enum that implements Role.
 */
public enum AppRoles implements Role {
  ADMIN,
  USER
}

2. Create an Roles enum that uses the app specific enum (for use with avaje-http controllers)

import java.lang.annotation.Retention;
import java.lang.annotation.Target;

import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.ElementType.TYPE;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

/**
 * Create an app specific Role annotation that uses the
 * app specific role enum.
 */
@Target(value={METHOD, TYPE})
@Retention(value=RUNTIME)
public @interface Roles {

  /**
   * Specify the permitted roles (using app specific enum).
   */
  AppRoles[] value() default {};
}

3. Use the Role enum on endpoints that we want the user roles check

      .routing(routing -> routing
        .get(ctx -> ctx.text("get"))
        .get("/multi", ctx -> ... ).withRoles(AppRoles.ADMIN, AppRoles.USER)
        .get("/user", ctx -> ... ).withRoles(AppRoles.USER)
      );

4. Implement and register the AccessManager

.accessManager((handler, ctx, permittedRoles) -> {
        final String role = ctx.queryParam("role");
        if (role == null || !permittedRoles.contains(AppRoles.valueOf(role))) {
          ctx.status(401).text("Unauthorized");
        } else {
          ctx.attribute("authBy", role);
          handler.handle(ctx);
        }
      })