Semantic elements for non-link links: media views buttons

[afercia]

All the buttons in the media views (wp.media.view.Button) are currently marked up as links with an attribute href="#" and they just "look" like buttons. For semantics and accessibility they should be buttons, see #26504

Thanks to backbone this would be a two-lines change but we should carefully check if anything breaks. Not 100% sure but to my understanding, given the way backbone attaches events, we should be safe. cc @wonderboymusic

Also, the modal menu items (wp.media.view.MenuItem) are links with an attribute href="#". See screenshot below.

If we decide to keep them as links, then they should act like links and be integrated with the media router and browser history. Or, we can simply change them in buttons and consider them just as controls that "switch" the views. Open to suggestions, any thoughs more than welcome.

See related #26550 for the buttons in media-template.php

[afercia]

First pass patch.

[wonderboymusic]

This appears to work fine. Will drop it in and see what breaks.

[wonderboymusic]

In 32464:

wp.media.view.Button should create <button>s, not <a href="#">s.

Props afercia.
See #32236.

[wonderboymusic]

Fixed, the rest of the work is in #26550