Fix failing E2E tests on trunk

[iamdharmesh]

Description of the Change

E2E tests started failing in WP 6.3 due to changes in WP 6.3 where editor is moved into an iframe. It seems that Cypress doesn't like this iframed approach and the editor fails to load. This means any tests that need to interact with the block editor (like creating a new post) won't work.

Somehow Cypress was not allowing the editor iframe to be loaded (I believe maybe due to cross-origin or insecure(HTTP) iframes). Adding config chromeWebSecurity to false has fixed this issue and the iframe editor started loading now.

As the block editor is loaded via iframe now, interaction with the block editor also needs to update. PR adds the getBlockEditor() command which returns wrapped editor iframe and returns a normal HTML body element in case E2E tests are running on older versions of WP (minimum env)

Closes #260

How to test the Change

Verify E2E test run from GH action or locally.

Changelog Entry

Fixed - Ensure our E2E tests work properly on WordPress 6.3

Credits

Props @iamdharmesh

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests pass.