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
(cherry picked from commit 6aa3befeb0f428ff32d4e3db8f66b8154a13e126)