Cleaned up ColorSchemeTab, added program checks, added firefox template

Matugen: added firefox (pywalfox) template
SidePanelToggle: use ProgramCheckerService for gpu-screen-recorder
ColorSchemeTab: use NCollapsible for matugen templates, use
ProgramCheckerService to detect available programs (for matugen
templates)
NCollapsible: create collapsible category

Commons/Settings.qml

@@ -449,6 +449,7 @@ Singleton {
         property bool foot: false
         property bool fuzzel: false
         property bool vesktop: false
+        property bool pywalfox: false
         property bool enableUserTemplates: false
       }