Add default mocks/stubs for testing Chaincode

[daanporon]

[elwaxoro]

For now, you can test with @theledger/fabric-mock-stub. Seems to work just fine alongside @kunstmaan/hyperledger-fabric-node-chaincode-utils

Ends up looking like:

import { expect } from 'chai';
import 'mocha';
let shim = require('fabric-shim');

import {YourChainCode} from '...';
import { ChaincodeMockStub, Transform } from "@theledger/fabric-mock-stub";

const cc = new YourChainCode(shim);

describe('Example', () => {
    it('Simple init', async () => {
        const mockStub = new ChaincodeMockStub("MockStub", cc);
        const response = await mockStub.mockInit("tx1", []);
        expect(response.status).to.eql(200);
    });
});