[FEATURE] Support Glue backend for Iceberg REST Catalog Service

### Describe the feature

### Describe the feature

Support AWS Glue Catalog as a built-in backend for the Gravitino Iceberg REST Catalog Service.

Users should be able to configure the Iceberg REST service with a Glue backend

### Motivation

AWS Glue Data Catalog is widely used as an Iceberg catalog backend. Gravitino Iceberg REST Catalog Service currently documents memory, Hive, JDBC, REST, and custom catalog backends, but not Glue.

### Describe the solution

_No response_

### Additional context

Add Glue as a supported value for gravitino.iceberg-rest.catalog-backend.

Start by locating the Iceberg REST Catalog Service configuration for `gravitino.iceberg-rest.catalog-backend` and reading how the documented memory, Hive, JDBC, REST, and custom backends are registered. Compare the existing backend setup with AWS Glue requirements; done means users can select Glue as a supported backend and the service uses the AWS Glue Catalog successfully.

Written by the indexing model from the issue text.