Introduce an adoption command in the wallpaper knsrc file

Summary:
Using the same semantics as the InstallationCommand, makes it possible for the
client to get a kns resource adopted.

Needs further standarization, I have implemented this on Discover and seems
to work just fine.

Reviewers: whiting, leinir, #plasma, mart

Reviewed By: mart

Subscribers: plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D4307

wallpapers/image/wallpaper.knsrc

@@ -30,3 +30,4 @@ Categories=KDE Wallpaper 800x600,KDE Wallpaper 1024x768,KDE Wallpaper 1280x1024,
 StandardResource=wallpaper
 Uncompress=archive
 
+AdoptionCommand=qdbus org.kde.plasmashell /PlasmaShell org.kde.PlasmaShell.evaluateScript 'for (var i in desktops()) { d = desktops()[i]; d.wallpaperPlugin = "org.kde.image"; d.currentConfigGroup = ["Wallpaper", "org.kde.image", "General"]; d.writeConfig("Image", "%f") }'