Add missing packages for SonicDE: KDE Gear 26.04.3, KF6 6.29.0, and support packages.

Also adds manually built Plasma 6.7.4 packages (plasma-systemsettings,
plasma-keyboard/kcm, plasma-print-manager, flatpak-kcm, sddm, sddm-kcm,
kdebugsettings) and provides plasma-desktop-doc from sonic-desktop-interface-doc.

Build-order regenerated.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

sddm/sddm-0.18.0-environment_file.patch

@@ -0,0 +1,11 @@
+diff -up sddm-0.18.0/services/sddm.service.in.env sddm-0.18.0/services/sddm.service.in
+--- sddm-0.18.0/services/sddm.service.in.env	2018-07-18 05:31:40.000000000 -0500
++++ sddm-0.18.0/services/sddm.service.in	2019-03-14 08:23:22.095498405 -0500
+@@ -7,6 +7,7 @@ After=systemd-user-sessions.service gett
+ [Service]
+ ExecStart=@CMAKE_INSTALL_FULL_BINDIR@/sddm
+ Restart=always
++EnvironmentFile=-/etc/sysconfig/sddm
+ 
+ [Install]
+ Alias=display-manager.service