Qt: Add ThemeSVGIconEngine to replace use of Qt SVG

Uses plutosvg to render icons with a different colour scheme dependent
on the text colour. No more duplicating all the icons.

scripts/appimage/make-appimage.sh

@@ -104,7 +104,7 @@ for i in $(find "$DEPSDIR" -iname '*.so'); do
 done
 
 echo "Running linuxdeploy to create AppDir..."
-EXTRA_QT_MODULES="core;gui;svg;widgets;xcbqpa;waylandcompositor" \
+EXTRA_QT_MODULES="core;gui;widgets;xcbqpa;waylandcompositor" \
 EXTRA_PLATFORM_PLUGINS="libqwayland.so" \
 DEPLOY_PLATFORM_THEMES="1" \
 LINUXDEPLOY_EXCLUDED_LIBRARIES="libwayland-cursor*;libwayland-egl*" \

scripts/appimage/make-cross-appimage.sh

@@ -177,14 +177,12 @@ declare -a QTLIBS=(
 	"libQt6DBus.so.6"
 	"libQt6Gui.so.6"
 	"libQt6OpenGL.so.6"
-	"libQt6Svg.so.6"
 	"libQt6WaylandClient.so.6"
 	"libQt6Widgets.so.6"
 	"libQt6XcbQpa.so.6"
 )
 
 declare -a QTPLUGINS=(
-	"plugins/iconengines"
 	"plugins/imageformats"
 	"plugins/platforminputcontexts"
 	"plugins/platforms"