David Hallas authored Mar 28, 2019 and Kurt Hindenburg committed Mar 28, 2019

Summary:
Fixes a few minor memory leaks found with address sanitizer.
The newTabButton and closeTabButton was not passed a parent and is not
deleted in the destructor of TabbedViewContainer which will cause them
to be leaked when closing a tab. Instead pass the TabbedViewContainer as
the parent.
The same goes for the profileMenu, it was not passed a parent pointer at
contruction and the setMenu function doesn't take ownership of it, so
therefore it was also leaked.

Backported the original version

https://phabricator.kde.org/D19634