drill

efbf4fc4 - DRILL-7272: Drill Metastore Read / Write API and Drill Iceberg Metastore implementation

DRILL-7272: Drill Metastore Read / Write API and Drill Iceberg Metastore implementation 1. Drill Metastore Read / Write API. 2. Drill Iceberg Metastore implementation in iceberg-metastore module. 3. Patches Guava Preconditions class for Apache Iceberg. 4. General refactoring. 5. Unit tests. 6. Documentation.