[Test] add test_model.jl

[odow]

Part of #1398

[odow]

@blegat I found test GLPK fails! It was trying to access ObjectiveFunction attribute, despite the fact that the model does not list in in the ListOfModelAttributesSet. Hurrah for full testing from modellike.

[odow]

julia> @testset "MOI" begin
           MOI.Test.runtests(
               GLPK.Optimizer(),
               MOI.Test.Config(),
               exclude = [
                   # GLPK treats this one as "INVALID_MODEL"
                   "test_constraint_ZeroOne_bounds_3",
               ]
           )
       end
Test Summary: | Pass  Total
MOI           |  476    476
[...]