debug: correct d0 at k+1 for MovingHorizonEstimator with collocations

[franckgaga]

The bug affects the MovingHorizonEstimator with TrapezoidalCollocation and OrthogonalCollocation transcriptions. It was using the wrong measured disturbances value $\mathbf{d_0}$ at the end of the windows.

The next measured disturbance $\mathbf{d_0}(k+1)$ is not available for the MHE, and the prediction form (direct==false) requires it at the end of the windows with the collocation methods (since piecewise linear measured disturbances is assumed, disregard of the h argument). This PR implement the correct logic in the for loop for the approximation $\mathbf{d_0}(k+1) \approx \mathbf{d_0}(k)$.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.22%. Comparing base (a6d5f55) to head (5e8c79a).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #452   +/-   ##
=======================================
  Coverage   97.22%   97.22%           
=======================================
  Files          28       28           
  Lines        6811     6812    +1     
=======================================
+ Hits         6622     6623    +1     
  Misses        189      189           

Flag	Coverage Δ
unittests	97.22% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.