Use properties to transform `ForEachObject` inputs

We currently convert parameters given in the Instrument's init method (can be strings for default or pre-defined values, scalar values when shared between all MOSAs or SC, or a dictionary, or a ForEachObject instance) to a ForEachObject instance.

This breaks when the user modifies the Instrument instance after initialization.

Two solutions:

• We can use properties to make sure that we correctly set those attributes at all times (performing verifications and conversions, maybe even reading and interpolating files).
  • Verifications, conversions and other pre-processing steps are performed multiple times if one changes the parameters multiple times before running the simulation.
  • On the other side, parameters are valid at all times (we check then when they are set). This means that users don't have to run simulations to see error messages.
  • We can prevent users to mutate parameters once the simulation has been run (and prevent potential mismatches between simulation results and parameters in the Instrument instance).
• Or delay those steps to simulation time, and only keep raw parametrization until simulate() is called.
  • Only perform verifications, conversions and others once before simulation.
  • Initialization and parametrization are computationally inexpensive. All the heavy lifting is performed in simulate().