Focus on search boxes on loading relevant admin pages

[WilliamWDTK]

Focus on the search box, such that one can start typing and hit enter, on loading (or a subsidiary page):

• /admin/bodies
• /admin/requests
• /admin/tags
• /admin/comments
• /admin/users
• /admin/tracks

Essentially, pages with search boxes in the admin interface.

(This may have a poor effect on navigability for keyboard navigators / those who use screen-readers.)