[WIP] correct maxsense in instantiate_function

[avinashresearch1]

Checklist

• Appropriate tests were added
• Any code changes were done in a way that does not break public API
• All documentation related to code changes were updated
• The new code follows the
  contributor guidelines, in particular the SciML Style Guide and
  COLPRAC.
• Any new documentation only uses public API

Additional context

Add any other context about the problem here.

[avinashresearch1]

Start to fix #9

@Vaibhavdixit02 Could I ask a couple of questions on expected semantics of OptimizationFunction.

• I see that OptimizationBase.instantiate_function constructs wrappers around f.grad etc. IIUC grad is meant to be provided by the user. For the case where sense = MaxSense, do we assume that they have provided grad, hess etc. respecting the correct sense?
• If so, that would meanwe only need to worry about the cases where we do the AD.

It appears we need to back calculate the sol.objective for the dfifferent solvers. Some already account for MaxSense but others require explicit specification.

SciML/Optimization.jl#925

I wanted to confirm that this is what is expected.