Support for single sc_ops for faster specific method in ssesolve and smesolve

[albertomercurio]

Checklist

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Description

The current implementation of ssesolve and smesolve only supports sc_ops to be either a Vector or a Tuple.

This constraints the solver to use the non-diagonal noise, as the diagonal one can only be implemented in the case of a single collapse operator. This cannot be inferred automatically, as the solver may depend on the length of sc_ops, creating type instability.

Here I implement the support for a single AbstractQuantumObject, which allows to implement the diagonal noise through multiple dispatch, thus without giving type instabilities.

The performances are 4 times better with respect to using a Vector of length one.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.20%. Comparing base (3029a54) to head (4029a5b).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #408      +/-   ##
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+ Coverage   94.16%   94.20%   +0.03%     
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  Files          46       46              
  Lines        2898     2918      +20     
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+ Hits         2729     2749      +20     
  Misses        169      169              

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