Make this part of ROOT.jl?

[Moelf]

I think this package should be part of ROOT.jl in the long run.

IIUC, this package exists because we think ROOT.jl APIs/bindings are too low-level to be used directly. Which means most users are expected to use this package. In that case, "wasting" the ROOT.jl name seems unwise, since users are left confused about why "ROOT.jl" is not actually useful despite its strong association with ROOT name.

This is also similar to how https://github.com/JuliaHEP/XRootD.jl works, it's more than a bare-wrapper because that wouldn't be very usable. So upstreaming the functions in this package into ROOT.jl would make ROOT.jl directly usable.

Of course, it would also have the benefit of streamlining development workflow if we just have a monorepo