🚀 Enhancement: Add Self-Relationship Support for Collections

### 🔖 Enhancement description Currently, Appwrite does not support self-referencing relationships within a collection. This feature request is to allow a collection to have a field that references itself, enabling hierarchical or recursive data structures. ### 🎤 Pitch Self-referencing relationships are essential for various use cases, such as: - **Hierarchical Data:** Building structures like categories, threads, comments, or organizational hierarchies. - **Tree-Like Relationships:** Enabling parent-child relationships within the same collection (e.g., a category having subcategories). - **Graph-Based Models:** Creating complex interconnections within a dataset. **Example Implementation:** - Allow a document in a collection to reference another document within the same collection via a **"Self-Relationship"** field. - Provide validation to prevent circular dependencies if needed. - Enable querying/filtering based on these relationships to traverse hierarchical structures efficiently. ### 👀 Have you spent some time to check if this issue has been raised before? - [x] I checked and didn't find similar issue ### 🏢 Have you read the Code of Conduct? - [x] I have read the [Code of Conduct](https://github.com/appwrite/.github/blob/main/CODE_OF_CONDUCT.md)