feat(ngSanitize): accept SVG elements and attributes

SVG elements and attributes are now accepted and sanitized by ngSanitize.

Closes #9578
Did you by any chance mean `xlink:href` ?
Also, should we add `action` to the list
(based on https://wiki.whatwg.org/wiki/Sanitization_rules#Attributes_whose_value_is_a_URI) ?