Allow untagged pages to appear in search results when sorting

[bglw]

Discussed in #255

^{Originally posted by huphtur March 24, 2023}
Have 2 types of pages on my 11ty site: collection (blog) pages, and one-off pages (eg an about page).

Added data-pagefind-body to <main> and all the pages get indexed, which is great.

I wanted to sort the blog posts by date, so added data-pagefind-sort="date" and sort: { date: "asc" }. My blog posts are indeed sorted, but now my one-off pages are not shown in the search result anymore.

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Pagefind should offer some way to configure how untagged results appear (or not) when sorting.

[stereobooster]

One of ways to approach this is to add configuration similar to what they have in SQL: NULLS FIRST, NULLS LAST