FIX EZP-22858: display in HTML comments the name of the used template

FIX EZP-22858 https://jira.ez.no/browse/EZP-22858
In dev environment, it displays in HTML comments the name of the used template with "START" and "STOP" (as in legacy when activating "template debug" in the debugOutput).
It was one of my favorite way to debug templates in legacy.