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/classes/Catalog.md

@@ -89,19 +89,30 @@ Drop an empty database. The server rejects nonempty databases.
 ### listDatabases()
 
 ```ts
-listDatabases(options): Promise<ListDatabasesResponse>
+listDatabases(options): DatabaseNames
 ```
 
-List one page of databases; pass pageToken from a response for the next page.
+Iterate lazily over all database names using `for await...of`.
+pageToken resumes from a saved token; omitted starts at the beginning.
+pageLimit limits each REST response, not the total; omitted uses the server default.
+Request errors are raised during iteration and terminate the iterator.
 
 #### Parameters
 
 * **options** = `{}`
 
-* **options.limit?**: `number`
+* **options.pageLimit?**: `number`
 
 * **options.pageToken?**: `string`
 
 #### Returns
 
-`Promise`&lt;[`ListDatabasesResponse`](../interfaces/ListDatabasesResponse.md)&gt;
+[`DatabaseNames`](DatabaseNames.md)
+
+#### Example
+
+```ts
+for await (const name of catalog.listDatabases({ pageLimit: 20 })) {
+  console.log(name);
+}
+```

docs/src/js/classes/DatabaseNames.md

@@ -0,0 +1,79 @@
+[**@lancedb/lancedb**](../README.md) • **Docs**
+
+***
+
+[@lancedb/lancedb](../globals.md) / DatabaseNames
+
+# Class: DatabaseNames
+
+A lazy async iterator of database names with pagination state.
+Returned by [Catalog.listDatabases](Catalog.md#listdatabases).
+
+## Implements
+
+- `AsyncIterableIterator`<`string`>
+
+## Methods
+
+### \[asyncIterator\]()
+
+```ts
+asyncIterator: AsyncIterableIterator<string>
+```
+
+#### Returns
+
+`AsyncIterableIterator`&lt;`string`&gt;
+
+#### Implementation of
+
+`AsyncIterableIterator.[asyncIterator]`
+
+***
+
+### next()
+
+```ts
+next(): Promise<IteratorResult<string, any>>
+```
+
+Fetch the next name, requesting another page only when needed.
+
+#### Returns
+
+`Promise`&lt;`IteratorResult`&lt;`string`, `any`&gt;&gt;
+
+#### Implementation of
+
+`AsyncIterableIterator.next`
+
+***
+
+### numPageResults()
+
+```ts
+numPageResults(): number
+```
+
+Number of names available without another REST request.
+
+#### Returns
+
+`number`
+
+***
+
+### pageToken()
+
+```ts
+pageToken(): undefined | string
+```
+
+Token for the next REST request. Initially this is the supplied starting token.
+Returns undefined after the final page is fetched, even if names remain cached.
+Drain the cache before saving a token to avoid skipping names when resuming.
+A failed request terminates iteration and retains its token for a new iterator.
+
+#### Returns
+
+`undefined` \| `string`