Lighthouse - Performance Tuning WordPress Plugin 4.2.0

* FIX: Remove db_server_info() method for WordPress 4.9+ and ClassicPress compatibility
* FEATURE: Add automatic background updater

* FIX: Exclude mailto and tel links from prefetching
* FIX: Sanitize query string parameter for SQL injection check
* FIX: Remove unused variable
* UPDATE: Update PHP recommendations
* UPDATE: Update WordPress recommendations
* UPDATE: Update WordPress compatibility
* FEATURE: Add page caching (browser caching)
* FEATURE: Add support for Cloudflare page caching headers

* FIX: Update User Agent check to prevent PHP 8+ warnings
* UPDATE: Update ClassicPress recommendations
* UPDATE: Remove all "Beta" labels
* UPDATE: Refactor code (WPCS)

* UPDATE: Only load ChartJS on Lighthouse pages to prevent conflicts with other getButterfly plugins

* UPDATE: Updated Thin UI to latest version (2.1.1)

* UPDATE: Removed Core Web Vitals and CrUX
* UPDATE: Added option to delete old settings, tables, files and logs on-demand
* UPDATE: Added option to remove the Custom Fields metabox from the post editor because it uses a very slow meta_key sort query

* FIX: Fixed update checker loop
* UPDATE: Removed CrUX report

* UPDATE: Refactored registration spam prevention to shortcircuit the `register_post` hook
* UPDATE: Refactored the blacklist log into an option counter
* UPDATE: Deprecated Core Web Vitals and CrUX
* UPDATE: Updated WordPress recommendation
* UPDATE: Updated ClassicPress recommendation

* FIX: Fixed undefined queries in WordPress back-end
* SECURITY: Add failed login count
* SECURITY: Refactor Dashboard cards and add a Security card

* UPDATE: Updated PHP and WordPress recommendations
* UPDATE: Used the IntersectionObserver API to only prerender links when they are visible. This will prevent the browser from prerendering links that the user may never actually interact with, which can improve the overall performance of the page. Additionally, using requestIdleCallback to schedule the prerendering logic to run when the browser is idle can ensure that the user's experience is not impacted by the prerendering process.
* UPDATE: Used the performance.now() function to measure the time it takes to execute the prefetching logic. The prefetch_throttle_delay value is adjusted based on the measured performance, ensuring that the prefetching logic only runs when the browser is able to handle it without impacting the user's experience.
* UPDATE: Optimized back-end performance by refactoring several loops
* UPDATE: Refactored code to allow for faster execution