Also apply autonumbering CSS to links in generated content

We had CSS that applied to our rendering of autonumbered links,
but not for raw <a rel="mw:ExtLink"></a> tags appearing in
generated content like templates.

Bug: 57420
Change-Id: Ic1585ecb1a133d16b7393ce0ce38a11b76cc2239
Merge "Also apply autonumbering CSS to links in generated content"