Refactor `DiscreteDependeciesConstraint`

[Scienfitz]

During implementation of 'DiscreteDependenciesConstraint' it was believed that all dependencies must be specified in a single constraint because application of the conditions cannot work independently. This assumption has to be re-checked. If its unnecessary, the interface would loose one layer of grouping. e.g.

• 'parameters' can only be length 1
• 'conditions' turns from list[Condition] to Condition
• affected_parameters turns from list[list[str]] to list[str]
• Depending on the potential decoupling from DiscretePermutationInvarianceConstraint the attribute permutation_invariant can be dropped