feat(number_theory/bernoulli): bernoulli_power_series (#6456)
Co-authored-by Ashvni Narayanan
Co-authored-by: Moritz Firsching <firsching@google.com>
Co-authored-by: Heather Macbeth <25316162+hrmacbeth@users.noreply.github.com>
Co-authored-by: Benjamin Davidson <68528197+benjamindavidson@users.noreply.github.com>
