[Bridges] add ExponentialConeToScalarNonlinearFunctionBridge

[odow]

This would enable:

julia> using JuMP, Ipopt

julia> begin
           model = Model(Ipopt.Optimizer)
           set_silent(model)
           @variable(model, x == 1.5)
           @variable(model, z)
           @objective(model, Min, z)
           @constraint(model, [x, 1, z] in MOI.ExponentialCone())
           optimize!(model)
           @assert is_solved_and_feasible(model)
           value(z), exp(1.5)
       end
(4.4816890628439685, 4.4816890703380645)

Now, it's an open question whether we should do this, but it comes up from time to time.

Latest is https://discourse.julialang.org/t/lazybridgeoptimizer-not-working-with-copy-to/123366

cc @thibault-vignon

[blegat]

I think it's fine to do by default