Input labels on the Add Media panel are not accessible

[johnbillion]

Splitting this out from #23561

The search box in the Add Media panel does not have an associated label so screen reader users receive no feedback as to the purpose of this text box.

Additionally, (not mentioned in #23561) the select menu for filtering media items does not have a label either and should do so.

[joedolson]

To save somebody else a little trouble, these fields are created in /wp-includes/js/media-views.js, between lines 3083 and 3171. media.view.AttachmentFilters and media.view.Search.

As of yet, I haven't pinned down exactly how the model for the HTML is sourced; I don't know the architecture of the media editor very well, and my minimal JS isn't serving me very well on this.

This seems like it should be a very simple task to complete, if somebody can find exactly where it should be done...

[r0uter]

I would like to prepare a patch for this bug. Please assign it to me.

[grahamarmfield]

Replying to r0uter:

I would like to prepare a patch for this bug. Please assign it to me.

Please feel free to add a patch - that would be great. I'll test it when it's done.

[SergeyBiryukov]

Sorry, didn't notice the 'good-first-bug' tag while looking into this.

I'm not very familiar with the media frame code, but 25102.patch​ seems to work for me. Inspired by a similar solution for the search input on Themes screen: tags/3.9.1/src/wp-admin/js/theme.js#L89​.

[wonderboymusic]

In 28839:

Dynamically prepend screen reader text to the attachment filters dropdown and the search box in the media modal.

Props SergeyBiryukov.
Fixes #25102.