added: setstate! now allows estimation covariance P̂ modification (if applicable)

[franckgaga]

We can now set the current estimation error covariance P̂ with the two setstate! methods:

setstate!(estim::StateEstimator, x̂, P̂=nothing)
setstate!(mpc::PredictiveController, x̂, P̂=nothing)

The matrix can be modified if estim is a:

• KalmanFilter
• UnscentedKalmanFilter
• ExtendedKalmanFilter

The two methods will throw an error if estim does not compute this matrix and P̂ != nothing, that is for:

• SteadyKalmanFilter
• Luenberger
• InternalModel
• MovingHorizonEstimator (only the estimation covariance at arrival is computed for the MHE, the current covariance is not available)

Also updated codecov github action to v5 in CI.yml

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.90%. Comparing base (4511057) to head (1367a55).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #192      +/-   ##
==========================================
+ Coverage   98.88%   98.90%   +0.02%     
==========================================
  Files          25       25              
  Lines        4205     4220      +15     
==========================================
+ Hits         4158     4174      +16     
+ Misses         47       46       -1     

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