security/py-biscuit-auth: Convert build to use PEP 517 and rename to PyPI name

• Rename port to PyPI name according to Python policy
• Move build completely to PEP 517
• Bump consumers: www/bunkerweb/Makefile
• Simplify Python discovery; the build frontend will pass the interpreter

New name: security/py-biscuit-python

Co-authored-by: Jochen Neumeister <joneum@FreeBSD.org>
PR: 297823
Approved by: joneum (maintainer)
Differential Revision: https://reviews.freebsd.org/D59133