Re-add human readable parser limit report
This mostly reverts commit
1255654ed5a89ed57491bda38f544ed87e3bc601.
This re-adds the human readable parser limit report, and makes a few
adjustments necessary for it to work properly.
* In EditPage::getPreviewLimitReport(), only generate the HTML report,
the JS variable will be added by OutputPage
* If there are multiple calls to OutputPage::addParserOutputMetadata(),
only use the limit report data from the first one.
* Only add the wgPageParseReport variable if limit report data is
available.
Bug: T142210
Change-Id: Iad2646acde79b8a59710bb9fd5fbbfea5a39c341