Replace per-catalog-type Druid classes with CatalogUtil.buildIcebergCatalog

Collapse `LocalCatalog`, `HiveIcebergCatalog`, `GlueIcebergCatalog`, `RestIcebergCatalog`
into a single property-map-driven catalog backed by `org.apache.iceberg.CatalogUtil.buildIcebergCatalog(name, options, conf)`.

## Motivation
- Current code re-implements per-catalog setup that Iceberg already provides
- 4 hand-written classes → 1 generic class
- Gain free support for `nessie`, `jdbc`, `bigquery` and any future Iceberg catalog
- Allow custom `catalog-impl=...` for organizations with private catalogs

Start by locating LocalCatalog, HiveIcebergCatalog, GlueIcebergCatalog, and RestIcebergCatalog, then read the org.apache.iceberg.CatalogUtil.buildIcebergCatalog(name, options, conf) entry point. Done means the four per-catalog implementations are replaced by one property-map-driven catalog that supports the catalog types and custom catalog-impl described in the issue.

Written by the indexing model from the issue text.