Test and Compatibility of new features with Builders

[preda-bogdan]

Things we need to achieve: We need to test background lazy-load feature with most popular builders.

• [x] Elementor
• [x] Divi
• [x] Beaver
• [x] Thrive

For each builder we need to add classes to watch via apply_filters( 'optml_lazyload_bg_selectors', [] ) filter in a compatibility file preferably.

Also we can have pages made for testing.optimole.com and build some cypress tests for this cases.

[selul]

for those, we will need test pages created on testing.optimole.com. We can create one subsite for each builder and set up some proper tests using cypress.