Add support for `tangent_vector_eval_at` for geodesics on manifolds integrated over multiple charts

[gh-FlorentinJ]

As reported on ​this question, tangent_vector_eval_at doesn't work if the option solve_across_charts is set to True in the geodesic declaration.

This is because the resulting interpolation is stored in a segmented way (one for each chart encountered during the integration), which is not expected by tangent_vector_eval_at.