docs: add examples for aria directives

[andrewseguin]

[github-actions[bot]]

Deployed dev-app for a0e3d182575447be7d438605d72d7720dd52ac19 to: https://ng-dev-previews-comp--pr-angular-components-32233-dev-essru9x3.web.app

Note: As new commits are pushed to this pull request, this link is updated after the preview is rebuilt.

[wagnermaciel]

I'm not sure I understand the distinction between docs examples and the current aria examples. What's the rationale for adding a new tab instead of making these changes in-place?

[andrewseguin]

This is a quick prototype-y check-in of work, starting initially as "here's a skeleton version of all the components with minimal styles", then turning into "here's a.dev examples with scoped styles".

We can add these as examples directly to the original tabs (and probably should). But we need to sort out the styles better since the current implementation is to share the same stylesheets across directives. On a.dev, we should have each example only display the CSS it needs, instead of a shared set across examples.

That said, we can leave this PR open/closed and avoid merging it. I just wanted to make sure my examples lived somewhere here to reference later in some form of version control