Endo E2E tests

Import behavior matrix

Import behavior readme
Import behavior matrix table

Real package imports E2E tests

Package imports tests readme

GH Actions Workflow for running e2e tests

A GH Action is set up to trigger on repository_dispatch coming from Endo repo to run the given ref against e2e tests and compare results with a snapshot.

The same workflow can also be triggered manually in this repo.

Temporarily the e2e test is also hooked on all pushes. We might want to disable that.