Write the bound duals in the AMPL solution using suffixes

[cvanaret]

At the moment, the call to ASL's write_sol_ASL writes the primal solution and the constraint duals in the .sol file. The bound duals should also be written using suffixes (see ASL documentation pp 20-22).
Reported by @odow.

[cvanaret]

Implemented in commit dd77f37.
The suffixes are lower_bound_duals and upper_bound_duals.

[odow]

Nice!

Currently, we've got these strings hard-coded into MOI:
https://github.com/jump-dev/MathOptInterface.jl/blob/ee313beac6e9853fe1ae3bab79befa0f51a27886/src/FileFormats/NL/sol.jl#L348-L364

So I guess we should make the sol reader more flexible as to how it parses suffixes.

Alternatively, we could make Uno call them ipopt_zL_out and ipopt_zU_out... but I don't know if that is a good or bad idea. I agree that the suffix stuff in ASL is horrible.

[cvanaret]

Making the sol reader more flexible would be advantageous, although I'm unsure which convention we could use.
Using the IPOPT suffixes in Uno would be a bit weird. Would it be an option - as a quick fix - to add a command line in Uno_jll's build_tarballs.jl the definition of Uno_jll.amplexe to replace Uno's suffixes with IPOPT's suffixes in the .sol file?

[odow]

I'll fix this in MOI jump-dev/MathOptInterface.jl#2566