add backgroundHints for the panel view
Summary:
This patch adds a variable called "backgroundHints"
which can be used with (NoBackground) through qml
in order to enable/disable the KWin effects for
a specific panel and the panel shadows in case the
effects are disabled.
Currently these effects are (Blur and Background Contrast)
Reviewers: Plasma, #davidedmundson
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D3282
FEATURE: 368384