Properly pass WordPress uploading errors to wp.Uploader

[koopersmith]

Currently, the media modal spits out a very generic plupload error whenever we encounter an error on the PHP side. This should not be the case. We're not formatting the error object in exactly the right format — we're missing the 'data' property.

The easiest way to test is to recursively remove write access to your uploads directory, and then try to upload a file. If you see "An error occurred in the upload. Please try again later.", that's the generic error. If you see an error specific to the file, that's WP's response.

[koopersmith]

ocean90 pointed out that we should probably add some CSS to allow long filenames to break.

[koopersmith]

Latest adds CSS to break words in errors and moves the max width from the error to the entire status div (to prevent huge progress bars).

[ryan]

In 22954:

Properly pass WordPress uploading errors to wp.Uploader.

Props koopersmith
fixes #22655