Add direct process noise covariance matrix

[sunsided]

This re-introduces the process noise matrix Q for the state transition process and refactors the previous process noise into an explicit control process noise.

[codecov]

Codecov Report

Attention: Patch coverage is 89.32384% with 30 lines in your changes missing coverage. Please review.

Project coverage is 94.21%. Comparing base (eb855d5) to head (16d8829).

Files	Patch %	Lines
...rs/types/direct_process_noise_covariance_buffer.rs	89.79%	15 Missing ⚠️
crates/minikalman/src/kalman/extended.rs	73.91%	6 Missing ⚠️
crates/minikalman/src/kalman/regular.rs	76.00%	6 Missing ⚠️
crates/minikalman/src/test_dummies.rs	70.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #32      +/-   ##
==========================================
- Coverage   94.47%   94.21%   -0.27%     
==========================================
  Files          42       43       +1     
  Lines        6013     6261     +248     
==========================================
+ Hits         5681     5899     +218     
- Misses        332      362      +30     

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