D27932: NetworkManager-Qt: Convert license headers to SPDX expressions

[Andreas Cord-Landwehr]

cordlandwehr added a task: T11550: Add SPDX License markers.

REPOSITORY
  R282 NetworkManagerQt

REVISION DETAIL
  https://phabricator.kde.org/D27932

To: cordlandwehr, jgrulich
Cc: kde-frameworks-devel, LeGast00n, cblack, GB_2, michaelh, ngraham, bruns