Add time varying parameters

[FlxPo]

Motivations

This PR adds support for time-varying parameter values, see #281 for details.

Changes

• Add ParameterProfile and SimulationStep utilities to represent and evaluate iteration-based parameter profiles.
• Add shared validated scalar aliases in validation_types.py.
• Allow motive parameters such as value_of_time, value_of_time_stay_home, and radiation_lambda to accept either constant scalar values or ParameterProfile values.
• Add Motive.get_parameters_at_step(step) to resolve step-varying motive parameters into scalar values for a given simulation step.
• Update destination sampling to use step-specific motive parameters when computing:
  • destination utilities
  • radiation-model destination probabilities
• Update state initialization to use the step-specific home parameters when building the initial stay-home state.
• Update state updates to use step-specific motive parameters when computing:
  • step activity utilities
  • stay-home / home-time utility
  • sink saturation parameters

Examples

The API to get a value of time for the work activity to change from 4 €/h to 8 €/h at time step 3 is :

WorkMotive(
    value_of_time=ParameterProfile(
        mode="step",
        points={ 
            1: 4.0,
            3: 8.0
        }
    )
 )

It's also possible to get a gradual change with linear interpolation, here the value of time will be 4, 6 and 8 at steps 1, 2, 3 :

WorkMotive(
    value_of_time=ParameterProfile(
        mode="linear",
        points={ 
            1: 4.0,
            3: 8.0
        }
    )
 )

The old API still works for constant parameters :

WorkMotive(
    value_of_time=4.0
 )

[codecov]

Codecov Report

❌ Patch coverage is 80.85106% with 18 lines in your changes missing coverage. Please review.
✅ Project coverage is 59.26%. Comparing base (db01023) to head (c2b6cba).

Files with missing lines	Patch %	Lines
mobility/simulation_profile.py	61.36%	17 Missing ⚠️
mobility/choice_models/population_trips.py	85.71%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #282      +/-   ##
==========================================
+ Coverage   59.06%   59.26%   +0.19%     
==========================================
  Files         129      131       +2     
  Lines        6738     6815      +77     
==========================================
+ Hits         3980     4039      +59     
- Misses       2758     2776      +18     

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