Implement AKM constructors

[ufechner7]

• Implement the constructor for KPS3
• Implement the constructor for KPS4
• Implement the constructor for KPS5
• Implement the constructor for SymbolicAWEModel
• Add tests

model = KiteModel(set) where set::Settings and KiteModel one of KPS3, KPS4, KPS5 and SymbolicAWEModel

[ufechner7]

model = KiteModel(set) where set::Settings and KiteModel one of KPS3, KPS4, KPS5 and SymbolicAWEModel
The model struct must have the fields set::Settings and integrator and am::AtmosphericModel and iter::Int64