NetworkManager-Qt: Convert license headers to SPDX expressions
Summary:
Convert license headers to SPDX expressions
and add license files as required by REUSE specification.
Reviewers: jgrulich
Reviewed By: jgrulich
Subscribers: kde-frameworks-devel
Tags: Frameworks
Maniphest Tasks: T11550
Differential Revision: https://phabricator.kde.org/D27932