Add license headers found in KDevelop

Quite a zoo of license headers which has assembled in the KDevelop sources in all the decades... :) Not sure the current mesh actually is compatible, but someone might do a calculation of that once the headers are processable.

Next to what I turned into samples and templates in this patch, I have some open questions still waiting in my local conversion branch. Could you give a peek at the original files and comment?

• What license is this? What to do? There is a whole set of ideal* files with that header:

• https://invent.kde.org/kdevelop/kdevelop/-/blob/master/kdevplatform/sublime/idealcontroller.h

• What to do about the "All rights reserved." in the "Copyright (c) 2002-2006 The RapidSvn Group. All rights reserved." here, drop that part?

• https://invent.kde.org/kdevelop/kdevelop/-/blob/master/plugins/subversion/svnclient.cpp

• How to convert the statements "This code was originally written by Judin Maxim, from the KDEStudio project.", "It was then updated with later code from konsole (KDE)." and "It has also been enhanced with an idea from the code in kdbg written by Johannes SixtJohannes.Sixt@telecom.at" here:

• https://invent.kde.org/kdevelop/kdevelop/-/blob/master/plugins/debuggercommon/stty.h

• What to do with those combined license statements, would that be resolved into LGPL-2.1-only as the only combination from both and given it is unclear what content is for which license header part:

• https://invent.kde.org/kdevelop/kdevelop/-/blob/master/kdevplatform/util/kdevstringhandler.cpp