Problem/Motivation
The current Media administration experience is not very visual, and does not look like what most people expect from a CMS.
Proposed resolution
We should update the view at /admin/content/media to look more modern - displaying a grid of media cards that show a preview of the media and metadata (attributes/fields) that make sense for each media item.
To give more flexibility to site builders and themers, each media item in the library is rendered in a new view mode called "Media Library", which is customizable like any other view mode.
This updated view will also be the basis for a new Field Widget, to allow visual selection of Media while editing/creating content. This widget will be added in another issue, but part of why this is being added in a new experimental module is to have a place for us to iterate on the widget and other code related to the Media Library experience.
Review the current patch. Discuss UX feedback.
Note for committers - on commit, please ensure that "jan.stoeckler, webflo, seanB, chr.fritsch, DyanneNova, yoroy, dennis-cohn, rfmarcelino, andrewmacpherson, benjifisher" is added to the issue credits. This is ported over from #2834729: [META] Create an MVP for adding and re-using Media.
User interface changes
The view at /admin/content/media looks different, but is functionally the same.
API changes
None.
Data model changes
None.
