SECURITY: Enhance CSS filtering in SVG files

* Filter <style> elements
* Normalize style elements and attributes before filtering
* Add checks for attributes that contain css
* Add unit tests for html5sec and reported bugs

Bug:69008
Change-Id: I732eece710f1bfaaeea1e5de541fcd4cfb375de7
Updated release notes and version number for MediaWiki 1.22.11

This is MediaWiki 1.22.11 security release.

Change-Id: I5a1abfc5e48cc2b3dc278eca5605dde0972fd91b
Merge branch 'REL1_22' of https://gerrit.wikimedia.org/r/p/mediawiki/core into REL1_22