We would like to revisit the `Authentication` class to make it provide better and easier to use interface to the consumers. 

#79809 enables run-as for all authentication schemes in addition to `realm` which is already supported. This adds more complexity to an `Authentication` object and how it should be used. For an example, building the role associated to an user now has to consider whether the user is the authenticated user or run-as user and the authentication scheme of the authenticated user. The existing `Authentication` class can answer all these question today. But its interface and internals are not aligned for these questions and the usage is error prone. For example, the `Authentication` object itself does not know whether the user has run-as. This information is kept by the `User` object. If the `User` object has an `authenticatedUser`, it's the run-as user. Otherwise it is not. But the information about realms for each `User` is directly kept in `Authentication`. Therefore, for full picture, the caller must check both `User` and `Authentication` realms and understands the nuance of their differenent combinations. 

- [x] Refactor CompositeRolesStore to separate roleDescriptors resolving (#80926)
- [ ] Move effective role descriptor checking from Resolver to CompositeRolesStore
- [x] https://github.com/elastic/elasticsearch/issues/81192
- [ ] Replace Authentication with AuthenticationContext in places other than CompositeRolesStore
x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/security/authc/Subject.java
domainRealm.getName(),
                            domainRealm.getType(),
                            creatorAuthRealm.getName(),
                            creatorAuthRealm.getType()
                        )) {
                            return true;
                        }
                    }
                    return false;
                }
            }
    }
    @Override
    public String toString() {
        return "Subject{"
            + "version="
            + version
            + ", user="
            + user
            + ", realm="
            + realm
            + ", type="
            + type
            + ", metadata="
            + metadata
            + '}';
    }
    private RoleReferenceIntersection buildRoleReferencesForUser(AnonymousUser anonymousUser) {
        if (user.equals(anonymousUser)) {
            return new RoleReferenceIntersection(new RoleReference.NamedRoleReference(user.roles()));