Add representation traits to graphql

[antirotor]

PR Checklist

Adding representation traits to the node in GraphQL.

Description of changes

Traits are JSON serialized data, in GraphQL represented as string to simplify model definitions.

Technical details

This is done so pipeline code can work with traits retrieved via graphql.

Additional context

Related PRs:
ayon-core#
#466
#431

[Copilot]

Pull Request Overview

This PR adds representation traits support for GraphQL by including a new JSON serialized field to simplify model definitions for pipeline usage.

• Added "traits" column retrieval in the representations resolver.
• Introduced a new nullable "traits" attribute in the representation node along with JSON serialization handling.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
ayon_server/graphql/resolvers/representations.py	Adds traits field selection in the SQL query for representations.
ayon_server/graphql/nodes/representation.py	Introduces a new nullable traits attribute and incorporates JSON serialization for the traits field.

Comments suppressed due to low confidence (1)

ayon_server/graphql/nodes/representation.py:111

• Consider explicitly checking for None (e.g., using record.get('traits') is not None) instead of a falsy check to ensure valid empty JSON objects are not discarded.

traits=json_dumps(record["traits"]) if record["traits"] else None,