Implement JWT generator to support scitokens authentication
This MR includes the addition of a JSON Web Token (JWT) generator. It allows the use of scitokens authentication with EOS, XRootD, and dCache storage elements.
However, please note that this generator has not been thoroughly tested with EOS and is currently inactive.
Despite this, I suggest merging this code to resolve issues with unit tests in the SFAPI compilation part.
Don't forget to make the unit-tests CI job mandatory to pass in .gitlab-ci.yml.
Edited by Volodymyr Yurchenko