mathlib3

168eeff2 - feat(analysis/constant_speed): define constant speed functions and prove existence of the arc-length reparameterization (#18208)

feat(analysis/constant_speed): define constant speed functions and prove existence of the arc-length reparameterization (#18208) Co-authored-by: Junyan Xu <junyanxumath@gmail.com> Co-authored-by: Rémi Bottinelli <bottine@users.noreply.github.com>