[Misc] Fix the build by refactoring a component that was doing too much.

xwiki-platform-core/pom.xml

...wiki/notifications/filters/NotificationFilterManager.java

...ications/filters/NotificationFilterPreferenceManager.java

...ns/filters/internal/DefaultNotificationFilterManager.java

.../internal/DefaultNotificationFilterPreferenceManager.java

...ions/filters/script/NotificationFiltersScriptService.java

...ns-filters-api/src/main/resources/META-INF/components.txt

...ilters/internal/DefaultNotificationFilterManagerTest.java

...ernal/DefaultNotificationFilterPreferenceManagerTest.java

...notifications/filters/watch/WatchedLocationReference.java

...iki/notifications/filters/watch/WatchedUserReference.java

...filters/watch/internal/DefaultWatchedEntitiesManager.java

...s/filters/watch/internal/DefaultWatchedEntityFactory.java

...ers/watch/internal/DefaultWatchedEntitiesManagerTest.java

...s/internal/email/live/DefaultLiveMimeMessageIterator.java

...fications/rest/internal/DefaultNotificationsResource.java

...ications/sources/internal/DefaultNotificationManager.java

...ki/notifications/sources/internal/QueryGeneratorTest.java