Re-add human readable parser limit report

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