debug: adequate padding for MHE dimensions printing

[franckgaga]

Before:

MovingHorizonEstimator estimator with a sample time Ts = 4.0 s:
├ model: LinModel
├ optimizer: Ipopt 
├ arrival covariance: KalmanFilter 
└ dimensions:
  ├10 estimation steps He
  ├ 0 slack variable ε (estimation constraints)
  ├ 2 manipulated inputs u (0 integrating states)
  ├ 6 estimated states x̂
  ├ 2 measured outputs ym (2 integrating states)
  ├ 0 unmeasured outputs yu
  └ 1 measured disturbances d

After:

MovingHorizonEstimator estimator with a sample time Ts = 4.0 s:
├ model: LinModel
├ optimizer: Ipopt 
├ arrival covariance: KalmanFilter 
└ dimensions:
  ├ 10 estimation steps He
  ├  0 slack variable ε (estimation constraints)
  ├  2 manipulated inputs u (0 integrating states)
  ├  6 estimated states x̂
  ├  2 measured outputs ym (2 integrating states)
  ├  0 unmeasured outputs yu
  └  1 measured disturbances d

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.56%. Comparing base (d0d9f11) to head (f65873c).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #363   +/-   ##
=======================================
  Coverage   98.56%   98.56%           
=======================================
  Files          27       27           
  Lines        5418     5422    +4     
=======================================
+ Hits         5340     5344    +4     
  Misses         78       78           

☔ View full report in Codecov by Sentry.
📢 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.