Move all Layout Builder operations into modal

Addressed issue mentioned by @imalabya. Please review.

The last submitted patch, 10: 3214458-10.patch, failed testing. View results →
- codesniffer_fixes.patch Interdiff of automated coding standards fixes only.

As the search in Choose block not working, added JS. Please review.

If for any reason one of the checkbox options is not chosen and the configuration form is saved that way, $route_names is no longer defined and you get complete page failures in Layout and the Layout Builder Modal configuration page--preventing you from being able to fix it. Thus, once done, this breaks LB on your site and requires some sort of configuration import or uninstallation of the module to reset.

Offering just a minor change to sakthi_dev's patch in #12 above that incorporates a failsafe variable initialization for $route_names to prevent this from possibly happening:

  // Get the use modal settings.
  $use_modal = $config->get('use_modal');

  $route_names = [];

  // If there are use modal settings, add the routes
  // that are in the settings to the route names array.
  if ($use_modal) {

The last submitted patch, 13: lb-operation-modal-3214458-13.patch, failed testing. View results →
- codesniffer_fixes.patch Interdiff of automated coding standards fixes only.

This patch same as #13 but incorporates the codesniffer fixes.

Manage Attributes for Layout Builder Sections Config module isn't accounted for.