[greenboard] Implement E2E tests

[joelalejandro]

This PR implements a basic suite of end-to-end tests for Counterfactual, using Selenium and chromedriver.

💚 Greenboard

An automated end-to-end test suite for Counterfactual, built with Selenium.

How does it work?

This package is executed from the monorepo's root, via yarn test:e2e.

How do I write a new scenario?

• Add a .spec.ts file into the tests/ folder.
• Instantiate the TestBrowser class and start an instance.
• Add the following steps:

await browser.openMetamask();
await browser.setupMetamask();
await browser.waitForMetamaskMainScreen();
await browser.setMetamaskNetwork("kovan");
await browser.openCounterfactualWallet();
await browser.authorizeWallet();

This will preconfigure Metamask and connect the Wallet UI with the Ethereum provider.

Contributes to #1852.

[spersico]

wow