Search for translated text in different locale

[dd32]

As a followup to #1496, this ticket is a followup enhancement for searching for translated text from a different locale.

For example

• 'Backup' will return the localised results and English results (When on de.wordpress.org)
• 'sicherung' will return only english results on wordpress.org, but on de.wordpress.org it'll return the localised results that actually have that word.
• 'sauvegarde' will return good results on fr.wordpress.org, but not on de.wordpress.org or wordpress.org.

[dd32]

In 13749:

Plugin Directory: Search: Weight the english plugin title higher for localised searches.

Most locales don't translate the WordPress.org readme.txt name field, and most don't alter the title at all.

When a locale doesn't translate this field (even as a 1:1 match) this results in plugins often being unable to be found by title.

This changes the weighting for the english search title from 0.00001 to 0.5 which results in the localised title being preferred, but should result in english matches still ranking in the results.

See ​https://wordpress.org/support/topic/what-happened-to-the-plugin-search-system/
See #6106, #7617.