D23725: ECMAddQtDesignerPlugin: pass code sample indirectly via variable name arg

[Friedrich W. H. Kossebau]

kossebau added a dependent revision: D23726: Designer plugin: adapt to 
pre-release API change of ECMAddQtDesignerPlugin.

REPOSITORY
  R240 Extra CMake Modules

REVISION DETAIL
  https://phabricator.kde.org/D23725

To: kossebau, #frameworks, #build_system, vkrause
Cc: kde-frameworks-devel, kde-buildsystem, LeGast00n, GB_2, bencreasy, 
michaelh, ngraham, bruns