Add license header found in kcachegrind & "Technology Preview License"?

There is a new variant of files copied from Qt sources, referencing some "Technology Preview License Agreement". I tried to do something similar as I found done for "Other Usage" with the LicenseRef-Qt-Commercial.txt, though comparing the actual text in kprocesslist.cpp, which refers to Nokia, with the text in the LicenseRef file, which refers to The Qt Company, and also not being a verbatim copy of the original text, I guess the proposed LicenseRef-Qt-Technology-Preview.txt file content will need some rework. Guess this is something for you @cordlandwehr to sort out?

I found that Technology Preview License Agreement text also in the SPDX wiki, but those bits seemed dropped and only the LGPL part handled: https://wiki.spdx.org/view/FileNoticeExamples#LicenseRef-Nokia-Qt-LGPL-Exception Which also makes me wonder if that license alternative should not simply be dropped during conversion, as any modification done to the file after it was copied/forked might rather be intended for the LGPL case only?

The actual text of the GPL-2.0-only licensed files had "KCachegrind" instead of "This program" in the text, but I replaced that manually first, to assist licensedigger a bit.