Improve SVG sanitizer to handle namespaced attributes
What does this MR do?
- Small refactor in the SVG sanitizer
- Enable already whitelisted namespaced attributes to be allowed
- Disable
xlink:hrefto reference any external resource
Fixes #18100 (closed) cc @stanhu
Are there points in the code the reviewer needs to double check?
Old code had no tests, this one adds minimal specs.
What are the relevant issue numbers?
Screenshots (if relevant)
Before:
After:
