r:panelMenu refactoring

tests rewritten
TestDragIndicator#testRendered fixed
page fragment for page fixed
test fof panel refactored
two tests for event handlers in progress bar fixed
test for toolbar group fixed
r:paneMenu fragment: waiting API unification, AdvancedInteraction
unification
tests for tooltip fixed
tests for queue fixed
accordion item: some basic tests configured to run only in plain template
one test for file upload fixed
stable tests configured to run only in plain template
tests for context menu fixed
tests for drop down menu fixed
tests for placeholder fixed