test: add PolicyRuleServiceValidation tests

package eu.teraflow.policy;

import context.ContextOuterClass.Device;

import context.ContextOuterClass.DeviceId;

import context.MutinyContextServiceGrpc;

import io.smallrye.mutiny.Uni;

public class MutinyContextServiceWrapper {

    private final MutinyContextServiceGrpc.MutinyContextServiceStub stub;

    public MutinyContextServiceWrapper(MutinyContextServiceGrpc.MutinyContextServiceStub stub) {

        this.stub = stub;

    }

    public Uni<Device> getDevice(DeviceId deviceId) {

        return stub.getDevice(deviceId);

    }

}