[kde-base/plasma-nm] Improve dependencies.

Package-Manager: portage-2.2.12
[kde-base/milou] Remove unused dependency.

Upstream commit: 45fa539ec0c8e96ae1f895144936291f9e09a3f7

Package-Manager: portage-2.2.12
Move KF5 libkscreen from x11-libs to kde-base as it is part of Plasma 5 proper.