Search: Allow for customizing sort order of search results (not [jobs])

From 2666802-zen

They would like to have a different sort order for the search results than what they have with just the [jobs] shortcode. For example, they would like [jobs] to show in order of date, and the results in order of Job Title.

Start at the [jobs] shortcode and trace how its normal listings and search results are ordered. Confirm how to configure separate sort orders for each path, then verify that regular listings remain date-ordered while search results can be ordered by Job Title; the issue does not name specific files or tests.

Written by the indexing model from the issue text.