Export just a single group

[wolfchimneyrock]

Feature or Problem Description

We are implementing a multi-tier multi-tenancy (based on groups) schema registry where each tier is an independent instance of apicurio registry.

we want to support a workflow where users can "deploy" i.e. copy the contents of their group from one tier to another, without our infrastructure having to manually fetch all the artifacts / versions / rules from the source tier and register in the destination tier.

Proposed Solution

the /admin/export api call could be modified to add an optional registryGroup parameter, which would restrict the rules / artifacts / versions exported to just those in the single group specified.

/admin/import wouldn't need any change, except that we would have to ensure that requireEmptyRegistry=false

Additional Context

in this case it would be ok for the contentId / globalId to differ between tiers