Testing email editor package export

[triple0t]

Switching to the exported editor packages.

Major notes

• Removed the packages directory
• Add Email Editor JS from npm and PHP from packagist
• Changed PHP Package namespace from MailPoet/EmailEditor to Automattic/WooCommerce/EmailEditor
• Update all actions and filters from mailpoet_email_editor_* to woocommerce_email_editor_
• Add the required CSS Inliner library (Pelago\Emogrifier\CssInliner)

Editor	Preview

[github-actions]

Test using WordPress Playground

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WordPress Playground is an experimental project that creates a full WordPress instance entirely within the browser.

Click here to test this pull request with WordPress Playground.

[triple0t]

Zip file, as the WordPress playground URL is experiencing errors.
mailpoet-email-editor-demo.zip

Playground link: https://playground.wordpress.net/#{%22landingPage%22:%22/wp-admin/edit.php?post_type=editor_demo_mail%22,%22preferredVersions%22:{%22php%22:%228.1%22,%22wp%22:%228.1%22},%22steps%22:[{%22step%22:%22login%22,%22username%22:%22admin%22},{%22step%22:%22installPlugin%22,%22pluginData%22:{%22resource%22:%22url%22,%22url%22:%22https://github-proxy.com/proxy/?repo=triple0t/email-editor-demo&branch=testing-email-editor-package-export%22},%22options%22:{%22activate%22:true}}]}