Merge remote-tracking branch 'origin/2.0.x' into 2.0.x-3052574-ajax

.gitlab-ci.yml

modules/facets_searchbox_widget/js/searchbox.js

...acets_summary/src/EventSubscriber/SearchApiSubscriber.php

src/EventSubscriber/ConfigurationSubscriber.php

src/EventSubscriber/SearchApiSubscriber.php

tests/facets_events_test/src/EventListener.php

tests/src/Unit/FacetSource/FacetSourcePluginManagerTest.php

...src/Unit/Plugin/processor/DependentFacetProcessorTest.php

tests/src/Unit/Processor/ProcessorPluginManagerTest.php

tests/src/Unit/QueryType/QueryTypePluginManagerTest.php

...s/src/Unit/UrlProcessor/UrlProcessorPluginManagerTest.php

tests/src/Unit/Widget/WidgetPluginManagerTest.php