Align statistical analysis methods for multi-trajectory solutions to QuTiP

[ytdHuang]

Checklist

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• Please read Contributing to Quantum Toolbox in Julia.
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Description

This PR introduces

abstract type TimeEvolutionMultiTrajSol end

struct TimeEvolutionMCSol <: TimeEvolutionMultiTrajSol
    ...
end

struct TimeEvolutionStochasticSol <: TimeEvolutionMultiTrajSol
    ...
end

For TimeEvolutionMCSol and TimeEvolutionStochasticSol we did some breaking changes :

• the origin field expect now stores the expectation values for all trajectories at each time points.
• remove field average_expect
• remove field runs_expect
• add field rng (random number generator) for reproducibility

Also, we introduce the following functions for statistical analysis:

• average_states
• average_expect
• std_expect

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.09%. Comparing base (a1d1627) to head (d49c89c).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #471      +/-   ##
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+ Coverage   94.08%   94.09%   +0.01%     
==========================================
  Files          49       49              
  Lines        3042     3049       +7     
==========================================
+ Hits         2862     2869       +7     
  Misses        180      180              

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