Investigate `mold` as a faster alternative to `ld`

@samuelpmishLLNL tried it out and tentatively noticed a ~30x speed up on linking our libraries.

https://github.com/spack/spack/blob/develop/var/spack/repos/builtin/packages/mold/package.py

https://github.com/rui314/mold

Start by reviewing Spack's var/spack/repos/builtin/packages/mold/package.py and the linked mold project documentation. Benchmark linking Smith's libraries with the current linker and mold, then record reproducible results and a recommendation for whether Smith should support or adopt mold.

Written by the indexing model from the issue text.