For ease of lookup, I changed the helper to return an array with keys
corresponding to the instanceId of the shipping methods. I couldn't see
anywhere else in the codebase where the keys would have mattered.
MAILPOET-5625
Until now we were using the same render() method and Twig templates for
the segments and lists pages. This commit separates them by creating two
different render() methods, one for each page, and also separing the
Twig templates. Only the translations remain shared as separating them
would be more involved and probably not worth it.
[MAILPOET-5392]
