helics: add new package (#15763)
helics: add new package (#15763)

* helics: add new package

* Remove FIXME boilerplate

* Use open @master: verison range for git dependency and remove mpi fix branch version

* Add blank line after spack import
iulian787/spack,LLNL/spack,LLNL/spack,iulian787/spack,iulian787/spack,LLNL/spack,iulian787/spack,iulian787/spack,LLNL/spack,LLNL/spack