Add AI Catalog Item Version to Duo Workflows API

What does this MR do and why?

Add AI Catalog Item Version to Duo Workflows API

It is require to relate Flow sessions created via Duo Wrokflow API with AI Catalog ItemVersions which define those flows.

Closes: https://gitlab.com/gitlab-org/gitlab/-/issues/568290

References

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Assure that AI catalog is enabled::Feature.enable(:global_ai_catalog)
2. Create a flow with AI Catalog
3. Make API call

curl -v -X POST \
    -H "Authorization: Bearer $GDK_API_TOKEN" \
    -H "Content-Type: application/json" \
    -d "{
        \"project_id\": \"$PROJECT_ID\",
        \"agent_privileges\": [1,2,3,4,5],
        \"goal\": \"$GOAL\",
        \"start_workflow\": false,
        \"environment\": \"web\",
        \"ai_catalog_item_version_id\": 1
    }" \
    http://gdk.test:3000/api/v4/ai/duo_workflows/workflows

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.