Fetch missing Navigation Timing metrics and mwLoadEnd.
Added support for fetching unloadEvent*, redirect*,
domainLookup*, domLoading and domContentLoadedEvent* from
the Navigation Timing API. Also send mediaWikiLoadEventStart
and end as relative to navigation start. Set user timing
for mediaWikiLoadEventEnd.
Bug: T109756
Change-Id: I1aaa31f87e31ec46990fe7420bc664b51927237e