Take 2 specification

[lucatume]

This PR only adds a specification file defining the expected code behavior and API.
The specification file is the place where examples of the desired flow, APIs and outcomes are collected.
I'm welcoming feedback to sync on the specification before implementing anything.

[bordoni]

I like where this is headed, potentially lets talk about avoiding non ZIP plugins/themes for now. Let packaging be something the plugin handles.

It prevents complexity from landing on TestFlow.

[bordoni]

From WP.org how do I point to a specific version? I might be missing that on the docs.

[shvlv]

Did we consider using existing tools like https://developer.wordpress.org/block-editor/reference-guides/packages/packages-env/ and https://developer.wordpress.org/block-editor/reference-guides/packages/packages-e2e-test-utils-playwright/? Or should we use a custom tool for more flexibility?

[bordoni]

@shvlv I am all for wp-env and e2e-test-utils-playwright to be part of the workflow here.

Our goal is to have a tool that implements these things in a way that would allow us to create lots of tests for all of our plugins without any barriers to entry in terms setting different ways to setup the dependencies.