[Nonlinear] parse x*x as x^2 in Nonlinear.Model

[odow]

Issue raised in PSORLab/EAGO.jl#150

I'll run solver-tests to see if there's any impact.

https://github.com/jump-dev/MathOptInterface.jl/actions/runs/16733837980

[odow]

JuMP failure is because of #2775

[odow]

It's an open question whether we should merge this. You might be tempted to say that this is an EAGO issue, not a JuMP/MOI issue.

They should detect structure rather than relying on the precise way that JuMP users write models or MOI lowers a quadratic.

[odow]

https://github.com/jump-dev/MathOptInterface.jl/actions/runs/16794100302

[blegat]

I also think that they should probably detect the structure, the user may still be able to write x * x, e.g., using @force_nonlinear ? On the other hand, this make to MOI makes sense. If we have a square in the ScalarQuadraticFunction, we should probably detect is as square.

[odow]

Yeah there's no right or wrong answer here. Very much open for debate