Differentiate docs with identical filenames

Currently if you have files with same name for example:

src/CMakeLists.txt
addons/CMakeLists.txt

opened in Kate, they show up as:

CMakeLists.txt | CMakeLists.txt (1)

This is very unhelpful. We can do slightly better by appending the dir name of the document for every such doc making the above:

CMakeLists.txt - src | CMakeLists.txt - addons

This isn't perfect either, but imo, it is definitely more helpful than placing a number beside the doc name, so maybe we can start here.

Further improvement could be to loop through all the files and find uncommon suffix and use that for the "- dir" part.

Screenshot:

BUG: 381532