Switch to using our own badge instead of jQuery.badge

With this change we will no longer be relying on JS for the badge
functionality. This will prevent the flash of unstyled content,
and allow wikis to locally override the styling (since the unread
class is now applied immediately).

I also went ahead and made the badge styling more closely match the
talk page message alert styling per Vibha.

Also removed the old full link optional behavior since we weren't
using it, and it would have been a pain to maintain.

Bug: 48165
Bug: 48001
Change-Id: Ie85d66afd5181d487d0bb2776ae14b121ea50d88
Merge "Switch to using our own badge instead of jQuery.badge"