[schema][kuzu] Declarative schema management

Problem to Solve

• Simple Schema Extension Contract: Currently, extending the database to support new nodes and relationships is cumbersome, and involves boilerplate like defining the columns themselves, and then also defining their Arrow relationships for ingestion, defining their relationships to other tables, defining "reader" structs for querying. However, all of this configuration is downstream of the column definitions and thus should be configured in a single location, possibly via macros.

Proposed Solution