Merge branch 'feature/simplify-time-dependency-angeli' into 'master'

Improve angeli test

See merge request !2607

(cherry picked from commit 846dd8b5)

75858e5c [test][ff][angleli] Cleanup time-dependent functions
6aa64286 [test][ff][angeli] Enable setting the start time
91110633 [test][ff] Integrate initial and boundary conditions for velocity for better accuracy
2f89ac0c [test][angeli] add test for averaging velocity initial and boundary conditions