Support JSContact (RFC 9553) for storing contacts

[xplosionmind]

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

Incompatibilities and limitations of the vCard contact storing standard.

Describe the solution you'd like

In the IETF’s RFC 9553, JSContact, a new standard for JSON Representation of Contact Data has been published. I believe this could be the final solution for the major issue of contact cards compatibility!

Additional context

• RFC 9554: vCard Format Extensions for JSContact
• RFC 9555: JSContact: Converting from and to vCard

[micbar]

In which scope do you see this proposal?

The default opencloud compose project uses radicale for calendar and contacts.

For a future groupware stack, we are already considering alternatives.