[Feature]: Convert objectives to constraints

[andgoldschmidt]

Feature Description

Background

There should be utilities that turn any objective into some appropriate constraint. The constraint should take in an objective and a value as arguments, and the output should be a constraint satisfying the desired condition.

For example,

function ObjectiveEqualityConstraint(objective::Objective, value::Float64) 
     objective - value = 0
end

function ObjectiveInequalityConstraint(objective::Objective, value::Float64) 
     objective - value > 0
end

This functionality has already been implemented in FinalUnitaryFidelityConstraint, which follows the format of UnitaryInfidelityObjective; the point of this issue is to generalize and abstract this concept.

Suggested checklist

• Pick a specific objective (e.g. UnitaryInfidelityObjective objective). Write a routine that creates a constraint from this objective. Compare to the existing constraint (e.g. FinalUnitaryFidelityConstraint).

Importance

1 (lowest)

What does this feature affect?

• quantum system construction
• problem setup
• problem solution
• problem performance
• solution analysis
• plotting
• documentation
• tests
• other (please specify below)

Other information

No response