Save an object per panel applet
Summary:
Instead of Item { Loader {} } just make the applet
container the Loader. Also saves some prop bindings
for sizing and centering the BusyIndicator, which
still appears correct.
Some props marked read-only as a bonus.
Reviewers: Plasma, mart
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D9152