Add an Artifacts.toml?

[amontoison]

For some research papers with François Pacaud and Sungho Shin, we rely on an Artifacts.toml to easily test our optimization solvers on ACOPF problems. It can be also useful here.
The content of Artifacts.toml is:

[PGLib_opf]
git-tree-sha1 = "0e8968a89b6ad43910a8eda4ec30656add35cf91"
lazy = false
    [[PGLib_opf.download]]
    sha256 = "f1421ce22f0a7b9de8a8b2111776b496348220192ad24aace392c3bf608706c2"
    url = "https://github.com/power-grid-lib/pglib-opf/archive/refs/tags/v23.07.tar.gz"

In our test, we can afterward do:

pglib_path = joinpath(artifact"PGLib_opf", "pglib-opf-23.07")

using PowerModels
pglib_opf_case78484_epigrids = ac_power_model(joinpath(pglib_path, "pglib_opf_case78484_epigrids.m"))