feat(rest): support configurable page sizes

[alexanderbianchi]

Which issue does this PR close?

Closes #2934.

What changes are included in this PR?

• Honor rest-page-size for namespace and table listings, resolving server defaults, client configuration, and server overrides in that order.
• Add REST_CATALOG_PROP_PAGE_SIZE and with_page_size(u32) to both REST catalog builders. Properties passed to load take precedence over the builder setter.
• Validate the effective page size after the lazy configuration handshake. Leave pageSize unset when no source configures it.
• Send pageSize on every page request and an empty initial pageToken to opt into pagination, while continuing to collect all results.
• Document configuring a REST catalog for DataFusion and add an end-to-end test proving that namespaces and tables from subsequent pages are visible through the provider and SQL. DataFusion continues to use the generic Catalog interface; no REST-specific production dependency or separate pagination setting is introduced.
• Update the REST public API snapshot.

Are these changes tested?

• REST tests cover configuration precedence, missing configuration, invalid values, minimum/maximum sizes, multipart parents, opaque page-token encoding, and propagation across pages.
• A DataFusion integration test uses a mock REST server to paginate namespace and table listings and checks the results through information_schema.tables.
• cargo test -p iceberg-catalog-rest -p iceberg-datafusion --lib --tests: 181 tests passed.
• cargo clippy -p iceberg-catalog-rest -p iceberg-datafusion --all-targets -- -D warnings: passed.
• Formatting, git diff --check, and the generated REST public API snapshot were checked.

AI Disclosure

The implementation, tests, and documentation were developed with assistance from an AI coding agent.