user-record: Add preferredSession{Type,Launcher}

These will be used by display managers to pre-select the user's
preferred desktop environment and display server type. On homed, the
display manager will also be able to set these fields to cache the
user's last selection.

shell-completion/bash/homectl

@@ -110,7 +110,9 @@ _homectl() {
                         --auto-login
                      -b --blob
                         --avatar
-                        --login-background'
+                        --login-background
+                        --session-launcher
+                        --session-type'
     )
 
     if __contains_word "$prev" ${OPTS[ARG]}; then
@@ -153,6 +155,12 @@ _homectl() {
             --language)
                 comps=$(localectl list-locales 2>/dev/null)
                 ;;
+            --session-launcher)
+                comps=$(find /usr/share/{x,wayland-}sessions/ -type f -name '*.desktop' -exec basename {} .desktop \; 2>/dev/null | sort -u)
+                ;;
+            --session-type)
+                comps='wayland x11 tty'
+                ;;
         esac
         COMPREPLY=( $(compgen -W '$comps' -- "$cur") )
         return 0