Make the LCT SECIR model a derived class of FlowModel

[lenaploetzke]

Motivation / Current Behaviour

Currently the LCT model is not derived from a class. The functionality is similar to the FlowModel. Also the files memilio/compartments/simulation.h for the CompartmentalModel and models/lct_secir/simulation.h for the LCT model do exactly the same. Both types of model should be combined.

Enhancement description

It should be no problem to make the LCT SECIR model a derived class of FlowModel to have a consistent project structure.

Additional context

For example: m_initial_values is used exactly like mio::CompartmentalModel::populations. If you want to, you could change its type to mio::Population, make the member public and rename it, so the models have more similar interface.

Originally posted by @reneSchm in https://github.com/SciCompMod/memilio/pull/941#discussion_r1502307064

Checklist

• [X] Attached labels, especially loc:: or model:: labels.
• [X] Linked to project