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### What

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obvious)? -->

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This PR add support for sparse fieldset parameter for the object types
of nested fields. Specify the fields to fetch using
`fields[NestedObjectType]` query parameter.
E.g:
```http
GET /v1/rest/default/institutions?fields[institution]=name,location,staff&fields[location]=city,country&fields[staff_member]=first_name,specialities&page[limit]=5
```
In the above example, `location` and `staff_member` are nested object
types of `location` and `staff` fields respectively.

### How
- Resolve the nested fields while building OpenDD query IR for a
json:api request.
- During planning, always resolve nested selection, if exists, instead
of selecting all available fields from the nested type. (This is only
applicable for model selection, the commands are still using older
approach for nested fields. This will be fixed in the future
iterations).
- Resolve sub-selections of graphql fields in opendd pipeline. Related
test snaps are corrected.
- Include sparse fieldset parameters for nested types in the openapi
schema
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steps)? -->
V3_GIT_ORIGIN_REV_ID: 587eecb79b6b8fac45f2eb6ffb37bf5fdcc7e374