Add Google Analytics events to Playground

[bgrgicak]

What is this PR doing?

This PR adds support for sending Google Analytics events.
Events are sent when the Playground website loads. There is a general load event to track the number of loads, and separate events for each step that send just the step name.

What problem is it solving?

We would like to better understand if people are using the features we build specifically what steps are used and how frequently.

How is the problem addressed?

By sending step names to Google Analytics we will be able to track the total number of times a step has been used and compare it to the number of events created.

Testing Instructions

• Checkout this branck
• Run npm run dev
• Add console.log(event, data); after this line

  wordpress-playground/packages/playground/website/src/lib/tracking.ts

  Line 21 in 05105b8

  export const addEvent = (event: GAEvent, data?: {[key: string]: string}) => {

  (Google Analytics only loads in production so we need to fake it locally)
• Open Playground
• Confirm that the events were triggered in the browser console

[adamziel]

Let's document what is being logged and why.

[bgrgicak]

I added a readme file with more details. Let me know if there is a better place to document this.

[adamziel]

I left two nitpicks, but other than that we're good to merge so I'm approving this PR 🎉

[bgrgicak]

Thanks for making these changes and merging!

[dmsnell]

Is there no consent request before loading these? I believe we need to enqueue analytics until we ask for and receive consent.

[bgrgicak]

Analytics were already on the site, this PR just adds extra events. But that's a good point we should add a consent request.

[bgrgicak]

#1060