Unify AL/recommendation events

[reckart]

Describe the refactoring action Whether accepting/rejecting/etc. a suggestion via the sidebar or main editor, the same event should be send

• enhance RecommendationAccepted/RejectedEvent with info about alternative suggestions;
• drop ActiveLearningRecommendationEvent which becomes unnecessary then
• optimally accept/reject/correct through a central method in the recommendation service instead of repeating the relevant code in the ActiveLearningSidebar and RecommendationEditorExtension.

Expected benefit More consistent events.