feat!: list_databases returns an iterator (#4442)

CatalogConnection.list_databases should return an iterator so that users
don't have to manually re-implement pagination. For those who do want
more control over pagination, add num_page_results and page_token to the
Iterator object, and also allow the iterator object to be created at a
specific page token.

python/src/lib.rs

@@ -64,6 +64,7 @@ pub fn _lancedb(py: Python, m: &Bound<'_, PyModule>) -> PyResult<()> {
     env_logger::init_from_env(env);
     m.add_class::<Connection>()?;
     m.add_class::<catalog::Catalog>()?;
+    m.add_class::<catalog::DatabaseNames>()?;
     m.add_function(wrap_pyfunction!(catalog::connect_catalog, m)?)?;
     m.add_class::<Session>()?;
     m.add_class::<Table>()?;