zfp: several package improvements (#21244)
zfp: several package improvements (#21244)

- add variants for build targets, language bindings, backends
- ensure selected variants are compatible with zfp version
- point to GitHub (not LLNL) tar balls
- add dependencies
- update link to homepage
- add maintainers

Co-authored-by: Massimiliano Culpo <a1d9c16990147e969def18cf36c066aa41dc29c3@gmail.com>
LLNL/spack,LLNL/spack,LLNL/spack,LLNL/spack,LLNL/spack