WIP: Use Hessian of Lagrangian funciton

[baggepinnen]

• This is waiting on a new release of SciMLBase containing the lag_h field in OptimizationFunction.
• Updating all the AD backends to provide the lag_h function.
• Update the Optim backend to make use of lag_h instead of manually assmebled version.

[codecov]

Codecov Report

Merging #366 (393785e) into master (124ee18) will decrease coverage by 35.50%.
The diff coverage is 50.00%.

@@             Coverage Diff             @@
##           master     #366       +/-   ##
===========================================
- Coverage   80.79%   45.28%   -35.51%     
===========================================
  Files           9        9               
  Lines         276      276               
===========================================
- Hits          223      125       -98     
- Misses         53      151       +98     

Impacted Files	Coverage Δ
src/function/function.jl	73.07% <50.00%> (-26.93%)	⬇️
src/function/finitediff.jl	6.97% <0.00%> (-86.05%)	⬇️
src/function/reversediff.jl	0.00% <0.00%> (-79.17%)	⬇️
src/function/tracker.jl	0.00% <0.00%> (-75.00%)	⬇️
src/function/zygote.jl	48.00% <0.00%> (-32.00%)	⬇️
src/function/mtk.jl	66.03% <0.00%> (-22.65%)	⬇️
src/function/forwarddiff.jl	83.33% <0.00%> (-11.91%)	⬇️

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