root: Add Version 6.24.00 (#22996)
root: Add Version 6.24.00 (#22996)

* 6.24 needs nlohmann-json (and disable the builtin one)
* Move the git url to the top (allows easier building of
  tags, etc)
LLNL/spack,LLNL/spack,LLNL/spack,LLNL/spack,LLNL/spack