Improve tab titles for documents with same name

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 | CMakeLists.txt - addons

The above isn't super perfect either, but it is more helpful than placing a number beside the doc name

Screenshot: