easyeffects: Make service compatible with v8.0.x (#8192)

Fixes #8185

The upstream easyeffects project has migrated from GTK to Qt, deprecating --gapplication-service and removing DBus integration. See #8185 for more details.
Tested with version 8.0.3 and 7.2.5 , uses lib.versionOlder cfg.package.version "8.0.0" to be backwards compatible.

    Removed DBus service configuration (Type=dbus, BusName)
    Move presets and config dir from $XDG_CONFIG_HOME to $XDG_DATA_HOME (new upstream location)

Other notes
Since they have moved config directory, it will warn show warnings because of empty dirs. These warnings will also show in the service until you remove them. I dont think this is a problem and new users will not experience this.

easyeffects --version
easyeffects: presets_directory_manager.cpp:140  Old /home/hausken/.config/easyeffects/output directory detected. Migrating its files to /home/hausken/.local/share/easyeffects/output
easyeffects: presets_directory_manager.cpp:149  Could not copy any file. Aborting migration of /home/hausken/.config/easyeffects/output
easyeffects: presets_directory_manager.cpp:140  Old /home/hausken/.config/easyeffects/irs directory detected. Migrating its files to /home/hausken/.local/share/easyeffects/irs
easyeffects: presets_directory_manager.cpp:149  Could not copy any file. Aborting migration of /home/hausken/.config/easyeffects/irs
easyeffects: presets_directory_manager.cpp:140  Old /home/hausken/.config/easyeffects/rnnoise directory detected. Migrating its files to /home/hausken/.local/share/easyeffects/rnnoise
easyeffects: presets_directory_manager.cpp:149  Could not copy any file. Aborting migration of /home/hausken/.config/easyeffects/rnnoise
easyeffects: presets_directory_manager.cpp:140  Old /home/hausken/.config/easyeffects/autoload/output directory detected. Migrating its files to /home/hausken/.local/share/easyeffects/autoload/output
easyeffects: presets_directory_manager.cpp:149  Could not copy any file. Aborting migration of /home/hausken/.config/easyeffects/autoload/output

tests/modules/services/easyeffects/example-preset.nix

@@ -27,6 +27,6 @@
 
   nmt.script = ''
     assertFileContent \
-      home-files/.config/easyeffects/input/example-preset.json "${./example-preset.json}"
+      home-files/.local/share/easyeffects/input/example-preset.json "${./example-preset.json}"
   '';
 }