Add listview and listviewitem roles to support interactive lists of interactive widgets, cards, tiles, etc.

[mcking65]

Closes #2036

• Adds two roles: listview and listviewitem.
• Implementation of A proposal for an interactive lists role
• Implementation of Proposal: Interactive Lists · w3c/aria Wiki

Related issues:

• #1325
• #1994
• #2162

Test, Documentation and Implementation tracking

Once this PR has been reviewed and has consensus from the working group, tests should be written and issues should be opened on browsers. Add N/A and check when not applicable.

• [x] "author MUST" tests:
• [x] "user agent MUST" tests:
• [x] Browser implementations (link to issue or commit):
  • WebKit:
  • Gecko:
  • Blink:
• [x] Does this need AT implementations?
• [ ] Related APG Issue/PR:
• [ ] MDN Issue/PR:

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Preview (#listview) (#listviewitem) | Diff