Render all section links as `li`s
Render all section links as `li`s

Previously, we would either render section links as either
`li`s in a list (if there were multiple questions in a
section) or as `a` elements (if there was just one question
in a section).

Rendering things two different ways wasn't really giving us
anything and it basically confused anyone who came into
contact with it (including me), as well as our functional tests.

We're presenting all section links identically, whether they're
the only question in a section or otherwise, so we should
render them consistently.

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