onEntryPointAdded event is misleading/not emitted at the proper time

Since #86 (closed) we are emitting onEntryPointAdded, but after some refactoring it's not emitted once addFolder returns, which means the event is emitted after the scan completed.

Since this event is meant to notify the user that their request has been received, it need to be sent as soon as the media library is aware of that request, not when it's starts being processed.

It might make sense to rename the event to something like onEntryPointQueue or similar