Empty post types array returned if no preset plugin provided

[paulrobertlloyd]

Describe the bug

A publication preset plug-in is optional, but the code in publication.js will only return post types if a preset is provided AND a user has specified their own overrides, otherwise it will return an empty array:

https://github.com/getindiekit/indiekit/blob/792c8c90b2ca1d65dd44198c89013fdbc65d3095/packages/indiekit/lib/publication.js#L88-L104

Expected behaviour

Post types should be returned if no preset plugin has been added to a user’s configuration, but post types have otherwise been configured.

Additional context

See: https://github.com/gerwitz/hgc-indiekit/blob/778fd9f71da939165ffce9d479fac04d0e3731b0/indiekit.config.cjs

/cc @gerwitz

[gerwitz]

I was wondering why https://github.com/roobottom/indiekit-2022 creates a plugin!