Update element to support native semantic definitions

[blackfalcon]

Is your feature request related to a problem? Please describe.

The current version of the auro-sidenav is void of any semantic meaning. This will result in incorrect SEO definitions and may cause accessibility issues.

Describe the solution you'd like

Update auro-nav to support the semantic roles as described in this article https://www.w3.org/WAI/ARIA/apg/patterns/breadcrumb/examples/breadcrumb/

That said, we cannot simply add nav HTML elements. This update should add the appropriate ARIA roles to the custom elements to give their semantic definition.

Describe alternatives you've considered

n/a

Additional context

This issue can be closed once the custom HTML structure fits the model of HTML5 semantic elements.