Setup integration tests in the Web IDE

MR: Pending

Description

Implement an integration test framework and some tests that exercises a happy path scenario where the Web IDE, GitLab Workflow Extension work in conjunction with a GitLab instance API.

• It's possible that the integration test simply runs the Web IDE Example App.
• A CI job should be added for test-integration (or whatever we want to call it).
• We want visual snapshot testing

Acceptance Criteria

• Integration test framework added that can run on top of the Example App && take visual snapshots
• At least one integration test added for a happy path - Users opens project, opens file, makes change, commits.
• CI job added to run integration test for

Investigation

• Maybe we can piggy back off of the GitLab UI project or the GitLab Workflow Extension...
• Let's look into https://webdriver.io or Cypress (or something else)...