Draft CI to automatically create a release from a tag, including a tar.gz filled

This PR aims to update the gitlab-ci to include a release_job that:

• is executed only when a new tag is executed on master or develop (feel free to comment otherwise)
• it creates a changelog depending on the list of commits from the last tag
• contains the typical output assets (the source code in zip, tar, ...) of the release with no submodules filled
• it adds an additional tar.gz file that contains the source code of all submodules. From this release, selected data folders are excluded to have a smaller release. Excluded files and folders are:
  • Files and fodlers starting with "."
  • Folders 'UCBlock/netCDF_files', 'tools/ucblock_solver/data', 'UCBlock/LP_files', 'CapacitatedFacilityLocationBlock/data' and 'MCFBlock/data'
  • Files and folders matching '.git*'

By doing so, the final release tar.gz file including submodules is about 30 Mb. Example is available here

To use this, there is the need to create a RELEASE_TOKEN variable that contains an access token with api rights to create the release