Match license keys by spdx

Summary:
KAboutLicense supports exporting a license as an spdx ID.
(https://spdx.org/licenses/)

However the KAboutLicense::fromKeyword doesn't match

We have a lot of metadata where people are using the spdx id
rather than the somewhat arbitrary keyword format that KAboutLicense
expects.

This adds a unit test to make sure all supported license keys match up
then expands the keyword list.

Subscribers: Frameworks

Tags: Frameworks

Differential Revision: https://phabricator.kde.org/D9437