Add external package support to xz (#19339)
Add external package support to xz (#19339)

* Add external package support to xz

* Flake-8

Co-authored-by: iarspider <19fbd54e0d93686a7814f6eac42d3d4acc146e9b@gmail.com>
LLNL/spack,LLNL/spack,iulian787/spack,LLNL/spack,iulian787/spack,iulian787/spack,iulian787/spack,LLNL/spack,iulian787/spack,LLNL/spack