Look in the correct path for shell update scripts.

Plasmashell was incorrectly listing update scripts from
XDG_DATA_DIRS/plasma/shells/<package>/updates when it should have been
listing from XDG_DATA_DIRS/plasma/shells/<package>/contents/updates.

This needed to be corrected because Plasma 5.5 is now bundling a
migration script for Kickoff favorites and installs it into the
correct location.

Distros may have to adjust the install location for their custom
update scripts for their Plasma 5.5 packages, if they haveany. Fedora
is known to be affected.

CCMAIL:rdieter@math.unl.edu
CCMAIL:kde-packager@kde.org

shell/scripting/scriptengine.cpp

@@ -894,7 +894,7 @@ QStringList ScriptEngine::pendingUpdateScripts(Plasma::Corona *corona)
     const QString appName = corona->package().metadata().pluginName();
     QStringList scripts;
 
-    const QStringList dirs = QStandardPaths::locateAll(QStandardPaths::GenericDataLocation, "plasma/shells/" + appName + QStringLiteral("/updates"), QStandardPaths::LocateDirectory);
+    const QStringList dirs = QStandardPaths::locateAll(QStandardPaths::GenericDataLocation, "plasma/shells/" + appName + QStringLiteral("/contents/updates"), QStandardPaths::LocateDirectory);
     Q_FOREACH(const QString& dir, dirs) {
         QDirIterator it(dir, QStringList() << QStringLiteral("*.js"));
         while (it.hasNext()) {