Content overview should contain language, or should default to English

[timcosgrove]

Description

By default, Drupal shows all translations of nodes in the admin content view (/admin/content) as well as the source language. This can result in a content view cluttered with different language variants - a node translated into two languages will result in 3 nodes in the content admin, and they will not be grouped together.

We need to decide how to approach this. One approach would be to provide a language filter so that the content admin only shows the selected language. Another might be to always show only English in the content admin, since all of our source content is English and all non-English will result from translation. Yet another approach would be a modified content admin view that groups translations with their English source.

Acceptance criteria

• [ ] Language is added as a column and filter to the Content overview view (/admin/content)
• [ ] The Content overview view language filter defaults to only showing English
• [ ] Ideally only people with permission to administer translations would have access to see the language column and filter

[EWashb]

@timcosgrove can you expound on this one? Should we have this in the other epic #12607? @laflannery and @dawnpruitt for visibility (since I'm rolling off)

[timcosgrove]

Moved to icebox; this is not part of MVP.