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.

docs/src/js/functions/connectCatalog.md

@@ -28,5 +28,7 @@ headers; opened database connections inherit authentication and client options.
 ```ts
 const catalog = await connectCatalog("https://my-server.example", { apiKey: "secret" });
 const db = await catalog.createDatabase("analytics", { existOk: true });
-const page = await catalog.listDatabases({ limit: 20 });
+for await (const name of catalog.listDatabases({ pageLimit: 20 })) {
+  console.log(name);
+}
 ```