quickshell: drop support for 0.2, require 0.3+

- Remove all compat code
- Rewire LegacyNetworkService to use Quickshell.Networking
- Add parentWindow to settings child windows

quickshell/Services/MultimediaProbe.qml

@@ -0,0 +1,7 @@
+import QtQuick
+// qmllint disable unused-imports
+import QtMultimedia
+
+// qmllint enable unused-imports
+
+Item {}