Render sources (IncidentPageLinks) in the Incident Page template

[harrislapiroff]

Some older articles have IncidentPageLinks associated with them, which should be rendered in the template. Newer articles have sources integrated into the body of the article, which is why it took a while to notice these missing.

It looks like work on this was started here but it's not pulling the correct context variables.

I haven't checked if the design matches, so for reference, they should look like this (Figma):

See #1587 for background.