Include instance owner party information in all APIs returning instance information

[martinothamar]

Description

As of #1229

We return instance owner party information (such as name) along with the rest of the instance information for the POST and GET (by instance ID) API endpoints, but not any others (se non-exhaustive list in linked PR).

It would be less surprising if the party information was added to all the places where we return the Instance today. This would mean we always return InstanceResponse and never Instance.

A counter argument would be that this information never changes, so it makes less sense to include as part of mutating operation responses such as data patching and user actions, but might still be worthwhile due to the potential surprise (there used to be only 1 variant).

Additional Information

No response

Tasks

No response

Acceptance Criterias

• Instance is no longer part of OpenAPI schema, we always return InstanceResponse in its' place