Fallback to simple search if baloo finds no results
Baloo has had repeated issues with finding files, recurring for years.
Currently a search with indexing enabled can fail to return results for files that do exist. This is a terrible user experience, especially for a core part of a computing experience.
This change adds a fallback so that if a search with baloo returns no results, we fall back to a simple search to ensure that if the file(s) exist, they will be found instead of the user being told that they don't exist.
While a true fix for baloo is needed, this change ensures that the user experience is good in the meantime.
Related bug: https://bugs.kde.org/show_bug.cgi?id=433967
Related bug: https://bugs.kde.org/show_bug.cgi?id=468256