Honour panelTakesFocus for other plasmashell types

Summary:
The semantics of a window taking focus on user interaction apply to more roles. See D25851.

Given it is used by `KWindowSystem::forceActivateWindow` in kwayland-integration, it makes sense to pass focus to the window once it gets this property set.

Reviewers: #kwin

Subscribers: kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D25968