Add indexing configuration option for stripping trailing slashes from result links

[bglw]

Discussed in #749

^{Originally posted by paulrudy December 8, 2024}
I'd like to suggest a Pagefind UI configuration option to strip trailing slashes in Pagefind results.

I understand that this can be done by passing a function to Pagefind's processResult config option as Astro's Starlight does.

But I think it might be useful enough, to enough people, to have as a standalone configuration option.

Thoughts:

I think the ideal would be to replace the keep-index-url indexing option with some sort of "URL behavior" option.

e.g. --url-format "trailing-slash" (default) or --url-format "keep-index" or --url-format "strip-trailing-slash"