Register only the relevant 3rdParty Theme class in the 3rdPartyTheme provider
Context
Reduce the plugin CPU usage: https://wp-media.slack.com/archives/CUT7FLHF1/p1704447166535709 There is only up to one theme used on a WordPress website but we currently register (and load) all 3dr party theme compatiblity classes.
Expected behavior When loading the plugin, only up to one 3rd Party theme compatibility class must be loaded. It must be the one corresponding to the theme currently used by the website, or none if no known theme is used. See this Slack suggestion
How to check results with XDebug https://wp-media.slack.com/archives/CUT7FLHF1/p1704728991213049
Not R&D anymore -> Let's make this production-ready if it is not already, and move forward for the next minor. Well done 💪