Merge branch 'fix-sanitize-svg' into 'master'
Update SVG sanitizer to conform to SVG 1.1 Original SVG sanitizer would strip out necessary elements and attributes. Use a custom Loofah scrubber since sanitize 2.x transformers are inadequate to handle case-sensitive SVG attributes since they parse documents as HTML instead of XML, which causes all SVG attribute names (e.g. `viewBox`) to be downcased. * SVG element list: https://www.w3.org/TR/SVG/eltindex.html * SVG attribute list: https://www.w3.org/TR/SVG/attindex.html Closes #14555 See merge request !3401