Allow .mw-echo-title-heading outside special page

This class was only being applied to notification output
on special pages and not in the overlay, move it so it can.

Additionally:
* bolds .mw-echo-title-heading same as the anchors it works with
* clean up a repeated rule against `.mw-echo-title a`

Change-Id: I579252399b39746f5aa2cfc51b5cd3b9b8b2cdb0
Merge "Allow .mw-echo-title-heading outside special page"