Add support for MOI.VariableName and MOI.ConstraintName

[odow]

Names from MOI do not make it to PATH. This makes printing and messages hard to read.

x-ref https://discourse.julialang.org/t/can-i-recover-variable-names-to-path-labels-jump-moi-pathsolver-path-jump/110703

The C API has

PATHSolver.jl/src/C_API.jl

Lines 742 to 743 in f03d0a7

	variable_names::Vector{String} = String[],
	constraint_names::Vector{String} = String[],

But we do not pass from MOI:

PATHSolver.jl/src/MOI_wrapper.jl

Lines 378 to 389 in f03d0a7

	status, x, info = solve_mcp(
	F,
	J,
	lower,
	upper,
	initial;
	nnz = nnz,
	silent = model.ext[:silent],
	jacobian_structure_constant = true,
	jacobian_data_contiguous = true,
	[k => v for (k, v) in model.ext[:kwargs]]...,
	)

cc @EliLazarus