ci: fix package names for Qt5/Qt6 builds

- Qt5 build: replace libqtxdg (Qt6 version) with libqt5xdg (Qt5 version)
- Qt5 build: remove kwayland (Qt6/KF6 version, not needed)
- Qt6 build: remove qt6-quickcontrols2 (non-existent, bundled in qt6-declarative)
- Qt6 build: add libqtxdg (Qt6 xdgiconloader)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: zccrs

.github/workflows/dtkdeclarative-archlinux-build.yml

@@ -35,7 +35,7 @@ jobs:
             extra-cmake-modules \
             gtest \
             librsvg libraw \
-            libqtxdg kwayland \
+            libqt5xdg \
             icu uchardet dbus spdlog gsettings-qt \
             dtkcommon dtklog \
             treeland-protocols dtkcore dtkgui
@@ -44,11 +44,12 @@ jobs:
         if: matrix.qt_version == 6
         run: |
           pacman -S --noconfirm --noprogressbar \
-            qt6-base qt6-tools qt6-declarative qt6-quickcontrols2 \
+            qt6-base qt6-tools qt6-declarative \
             qt6-wayland qt6-svg qt6-imageformats \
             extra-cmake-modules \
             gtest \
             librsvg libraw \
+            libqtxdg \
             icu uchardet dbus spdlog \
             dtkcommon dtk6log \
             treeland-protocols dtk6core dtk6gui