feat: add support for multipart namespaces

[dingo4dev]

Rationale for this change

This PR introduces support for multi-part namespaces, enabling more flexible and organized data layouts. This feature allows users to structure their tables within nested hierarchies (e.g., ('database', 'schema', 'table')), which is a common pattern in many data warehouse systems.

The level of support varies depending on the underlying catalog implementation. Here's a summary of the changes:

Catalog Implementation	Multi-Part Namespace Support	Notes
REST Catalog	✅ Yes	Fully supports multi-part namespaces as defined by the REST spec.
DynamoDB Catalog	✅ Yes	The namespace is represented as a composite key.
File Catalog	✅ Yes	Namespace parts are mapped to directory hierarchies in the file system.
In-Memory Catalog	✅ Yes	Supports multi-part namespaces for testing purposes.
Hive Catalog	❌ No	Spark and Hive Metastore do not support multi-part namespaces.
Glue Catalog	❌ No	Uses AWS Glue databases which do not support multi-part namespaces.

closes #2240

Are these changes tested?

Are there any user-facing changes?