PluginManager: Introduce a getObjects() function taking a predicate

Change-Id: I8a822d76a3dc358de48e96801e4e531f3bbb8669
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@digia.com>
Reviewed-by: hjk <hjk121@nokiamail.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>
Rewrite ::getObjects usage to use predicate version

This makes the code easier to read and shorter.

Change-Id: I6d582bd9861aa0208565301f61f098e9313b6c89
Reviewed-by: hjk <hjk121@nokiamail.com>
QmlDesigner.PropertyEditor: Enabling tooltips for labels

The old property editor did support tooltips and many labels
have properly defiend tooltips.
In QtQuick.Controls we have to use private API for tooltips
to show up.

Change-Id: If1c50b58e8388b8846c2dd07fcd326f09d67d127
Reviewed-by: Marco Bubke <marco.bubke@digia.com>