Python has int.bit_length(), but Sage has Integer.nbits().

In this patch, we add Integer.bit_length() for compatibility with int.

Among other things, this change should make it easier to switch from Python to Sage mid-development, which currently requires replacing all calls to .bit_length() or adding casts to int.

This helps with

• Meta-ticket: improve compatibility with the Python library and Python packages #29728: Meta-ticket: improve compatibility with the Python library and Python packages

Component: basic arithmetic

Author: Lorenz Panny

Branch: fb8f165

Reviewer: Frédéric Chapoton

Issue created by migration from https://trac.sagemath.org/ticket/33676