UKF: Unit tests + fix

[rolalaro]

• [FIX] Fixed a problem in the init function that caused an undefined behavior when calling filter or predict for the first time
• [TEST] Added some unit tests for the UKF

[codecov]

Codecov Report

Attention: Patch coverage is 28.16901% with 102 lines in your changes missing coverage. Please review.

Project coverage is 45.12%. Comparing base (20cf165) to head (41c46be).
Report is 121 commits behind head on master.

Files	Patch %	Lines
example/kalman/ukf-linear-example.cpp	18.64%	48 Missing ⚠️
example/kalman/ukf-nonlinear-example.cpp	24.00%	38 Missing ⚠️
example/kalman/ukf-nonlinear-complex-example.cpp	48.14%	14 Missing ⚠️
modules/core/src/math/kalman/vpUnscentedKalman.cpp	66.66%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1417      +/-   ##
==========================================
+ Coverage   44.44%   45.12%   +0.68%     
==========================================
  Files        1082     1087       +5     
  Lines      109248   109976     +728     
  Branches    18675    18817     +142     
==========================================
+ Hits        48552    49631    +1079     
+ Misses      60696    60345     -351     

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