Merge branch 'hotfix/#6298-#6263-handle-regular-elements-as-target-of-collection-element'

Close #6298
Use constants for events in Zend\Db\TableGateway\Feature\EventFeature
Add an empty newline
fixes cs
#6569 #7066 - minor CS fixes (trailing whitespace, spacing)
Merge branch 'hotfix/#6569-#7066-use-constants-in-zend-db-tablegateway-event-feature' into develop

Close #6569
Close #7066
Forward port #6569
Forward port #7066