feat(ngHref): bind href attribute to ng-href attribute in case SVG el…

[m-amr]

…ement

What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)
Feature that solve #15618

What is the current behavior? (You can also link to an open issue here)
href attribute doesn't bind to ng-href in case of SVG element

What is the new behavior (if this is a feature change)?
href attribute binds to ng-href in case of SVG element

Does this PR introduce a breaking change?
No

Please check if the PR fulfills these requirements

• The commit message follows our guidelines: https://github.com/angular/angular.js/blob/master/CONTRIBUTING.md#commit-message-format
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

Other information:

[gkalpak]

I think we will need a lot more changes (e.g. here, here, here and probably elsewhere) and more tests and security reviews. TBH, I am not sure it is worth it at this point (until the spec is finallized and implemented by browsers).