D7941: use Kirigami Theme for colors

[Marco Martin]

mart added reviewers: Plasma, Kirigami, hein.

REPOSITORY
  R858 Qt Quick Controls 2: Desktop Style

REVISION DETAIL
  https://phabricator.kde.org/D7941

To: mart, #plasma, #kirigami, hein
Cc: plasma-devel, ZrenBot, progwolff, lesliezhai, ali-mohamed, jensreuterberg, 
abetts, sebas, apol, mart