Add copyright headers

Dear @lga ,

We analysed the current code in the 3 MDM subrepositories and found that your python source code files included a copyright header, in SPDX short version, while the rest of the files didn't have a header. We have produced a Merge Request to add the headers to the rest of the files. We have added the same SPDX header that you had already provided in the python files.

We invite you to check each change because there are some cases in which the addition of the header can create issues, like in files which are input for another processes where a header may not be expected. Please have a look at them.

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

Thanks a lot

cc @mjahn0qp