filenamesearch: Add missing translation domain
This kio-worker seems to have always been missing a translation domain.
Add the translation domain definition and Messages.sh, so the user visible strings can get translatable.
Testing
Currently it has only one string ("Search Folder") which is the UDS type it provides and can be seen on dolphin search info panel.
Without this patch, doing a non-indexed search, we'll get the following error messages:
kf.i18n: KLocalizedString: Domain is not set for this string, translation will not work. Please see https://api.kde.org/frameworks/ki18n/html/prg_guide.html msgid: "Search Folder" msgid_plural: "" msgctxt: ""
It might look small for a whole catalog, but we're doing the same for other workers like info
.
CCing: @teams/i18n @ltoscano to make sure this is correct