build: setup Cypress for end-to-end testing

[arturovt]

@joeldenning

In short what I've done:

• added integration folder with 2 folders inside:
  • shop (simple Angular application with routing)
  • portal (single-spa web app)
• added cypress. Added scenario for the "back button" issue when change detection gets broken

What changes will be required further?

• currently package.json of the NPM package is located in the root folder
  • the root package.json should contain only devDependencies and be private: true
• NPM package.json should be isolated inside the src folder
• single-spa-angular/browser-lib should be built with ng-packagr since it emits Angular compatible code that can be proceeded by both view engine and Ivy compilers

[joeldenning]

This is a big one - will try to make time for it today, but it might be tomorrow before I can look at it.

[joeldenning]

Thanks for all of your work on this - this will really help. I have a few initial questions before diving deeper into the specifics.

[joeldenning]

Thanks again for all your work on this - I am signing off for the day but will look at this tomorrow morning.

[joeldenning]

This looks good to me! Thanks for your work on it.