Fix Page Builder content translation and PHP 7.4 compatibility

[SamueleMartini]

Summary

• Fixed widget content_settings translation using JSON decode/encode instead of unreliable regex
• Added translation of repeatable items and widget preview inside content_settings
• Fixed text/heading content types corruption during HTML encoding
• Downgraded PHP compatibility to 7.4
• Version 1.11.2

Test plan

• Duplicate a CMS page with Page Builder widgets (slideshow, grid with repeatable items)
• Translate the page and verify content_settings values are translated in DB
• Verify Page Builder editor shows translated widget text
• Verify text/heading content types are not corrupted after translation