Domain tags on content / "soft" multitenant

[mapkyca]

Is your feature request related to a problem? Please describe.

In conversation it was raised that some folk want to run a multiple site instance of known, but with the ability to "mix in" content from one domain into another.

Each domain could have individual configs based on domain, but allow users to optionally migrate and for selected feeds to mix in content from other sites

This is not quite going as far as the complete segregation offered by multi tenant, but more of a halfway prospect.

Describe the solution you'd like Extend core functions to tag content with a site id on creation. Retrieval functions will default to retrieving content from the current site, but can optionally retrieve from one or more different site ids.

Describe alternatives you've considered Other option would be do do this via API, but that makes mixing feeds a complicated prospect.

[mapkyca]

To be clear, I'm thinking a site id column, rather than an actual "tag"