applets/kickoff: fix "ReferenceError: plasmoid is not defined" error
This error happened because KickoffListView was asking for metrics that come from a KickoffListItem living in KickoffSingleton. However that item needs access to a config property to determine its own size, and singletons can't access per-applet config data, because they're shared across all instances of the app.
This commit fixes the issue by moving the metrics object for the variable-size list item from the singleton to the root item of the applet instance.
Edited by Nate Graham