Add Copyright headers

Dear @dalal ,

We analysed the current code and found that, in most of the files you had applied the short spdx copyright header version, while in a few cases the copyright headers were missing from the source code files. We have produced a Merge Request to show mainly the type of headers we expect when IP Reviewing open source code, and add them.

We invite you to check each change in case the addition of the header creates issues, like in ".txt" files where we are not sure if comments or headers are expected. Please have a look at them.

You'll notice we've assigned ownership to "fortiss Gmbh", we took it from the headers you added. If this is not the correct name or owner, please change it, or let me know and I will correct it. Use this Merge Request issue for this.

You will notice as well that in each file there is a placeholder for the Contributors (last section in the header), and we have already added you as Author. Feel free to add others' names there.

Feel free to be inspired and/or accept the whole Merge Request.

Thanks a lot

cc @mjahn0qp