fix(get_asset_details): include multiValueAttributes in GQL query

[Asubtlecoderrr]

🎯 What does this PR do?

Problem

get_asset_details silently drops attributes backed by MultiValueListAttributeType (multi-select dropdowns). These attributes allow selecting one or more values from a predefined list. In Collibra's GQL schema, they are stored under multiValueAttributes — a separate field that was never included in the query. Single-select attributes (SingleValueListAttributeType) work correctly as they are stored under stringAttributes. As a result, any multi-select attribute is completely absent from the response with no error or warning, regardless of whether one or multiple values are selected.

A secondary issue: resolveAssignableAttributes built its isSet map from only the
four GQL attribute lists, so selection attributes were always marked isSet: false.

Fix

• Add multiValueAttributes(limit: $attributesLimit) { type { name } } to the GQL query.
• Add MultiValueAttribute struct and field to Asset.
• Collibra's GQL schema exposes no scalar value field on MultiValueAttribute
  (stringValue and value are both undefined). Values are enriched via a
  best-effort REST call to /rest/2.0/attributes?assetId=… after the GQL fetch.
• Include MultiValueAttributes in resolveAssignableAttributes's isSet map.

Testing

Verified locally against a real Collibra instance: get_asset_details for asset
019fd154-9501-72be-b2fc-cb99858b5ae1 now returns
multiValueAttributes: [{ type: { name: "Source Release" }, value: "CE" }]
and assignableAttributes shows isSet: true for it.

✅ Checklist

• My code follows the style guidelines of this project.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation (if needed).
• My commit messages follow the Conventional Commits standard.