[PULP-713] Add support for new JSON simple index #625
Description
Describe the solution you'd like
Add support for the new JSON simple index https://peps.python.org/pep-0691/ for our publications + distributions.
Bandersnatch>=6.0.0 already supports writing the new format of simple pages. Look into using their existing code.