Add language display and filter to content admin views

[swirtSJW]

As a content editor or publisher I would like to be able to easily see what language a page is, be able to filter by particular languages and have easy access to translating a page so that I can find pages that are translated or easily create translations.

AC

• [x] /admin/content and /admin/content/bulk displays a "Language" column showing the language of each page in the content list.
• [x] /admin/content and /admin/content/bulk has a filter that allows for filtering by available languages (english and spanish)
• [x] For each content type in the admin content list that is translatable, there should be a "Translate" link that takes the user to the tab where a new translation can be added for that node.

[swirtSJW]

Discussed with @kevwalsh on screenshare that the Language column should be the last column of the table and that the filter should match the order of the table.