Revision: associatedfiletypes capability rework

[AleixMT]

This capability needs a rework since it is based in old versions of the customizer using launchernames or launchercontents which are very much deprecated currently.

It also does not work in the current versions of Linux since the file used to list the mime types can change depending on things like distro in Linux.

Basically we need to understand better the association of file types to desktop launchers accross the major Linux distributions that we support in order to write a robust implementation for this capability.