Migrating JSON Schema Validation from RefResolver to referencing

Snakemake utilizes JSON schema validation to ensure the correctness and consistency of configuration files and other data structures. Previously, the `RefResolver` class from the `jsonschema` library was used to resolve references within these JSON schemas, allowing for modular and reusable schema definitions. An attempt was made here to update this functionality to the referencing library, all while keeping the existing tests passing.