QAFE-967 [READY] [S] As QAFE developer I want to execute an event with
"toggle" built-in on the client-side when a button is clicked so that I
can execute toggle without server-side round-trip.
- Added ToggleHandler for handing client-side events
- Added ToggleAssembler for sending server-side components to
client-side
- AbstractEventItemAssembler now contains
assembleBuiltInComponent-function to reuse for other client-side
built-ins.