libtaskmanager: find desktop file in cwd
For some Electron apps, the pid of the main window may not have enough information to provide a desktop file due to the multiprocess architecture. So try to find a desktop file with the same name in the same folder (or cwd), and if there is a match, create a temporary service from the file to read its icon.
BUG: 481490 FIXED-IN: 6.0