WICKET-5732 Improve component queuing and auto component

(code review with MArtin Grigorov)
WICKET-5732 tag 'wicket:head' can be skipped during queuing.
WICKET-5732 added IQueueRegion#getRegionMarkup to specify the markup of
queue region.
WICKET-5732 (code review with MArtin Grigorov)
WICKET-5732 Tab formatting, no functional change.