Optimized keywords filters by using native for loop.
Item conversion and transient-persistent property handling:
 * convert note to task
 * made ConvertService helper functions private
 * made ExtendedItemService helper functions private
 * increased performance by replacing forEach loops with native for loops
 * support for multiple add extra transient property callback function addTransientProperties
 * public detachTransientProperties function in NotesService
 * public attachTransientProperties function in TasksService
 * ConverService unit tests