feat: 世界情報にエンティティおよびURNに基づくメソッドを追加

[shima004]

This pull request adds new utility methods to the WorldInfo class to make it easier to retrieve entities and their IDs, either for all entities or filtered by URNs. These additions improve the API's usability and flexibility when working with entities in the world model.

Entity retrieval enhancements:

• Added get_entities and get_entity_ids methods to return all entities and their IDs, respectively, from the world model.
• Added get_entities_of_urns and get_entity_ids_of_urns methods to retrieve entities and their IDs filtered by a list of EntityURN values.

Dependency update:

• Imported EntityURN from rcrscore.urn to support the new URN-based filtering methods.