feat: remote index stats (#1702)

BREAKING CHANGE: the return value of `index_stats` method has changed
and all `index_stats` APIs now take index name instead of UUID. Also
several deprecated index statistics methods were removed.

* Removes deprecated methods for individual index statistics
* Aligns public `IndexStatistics` struct with API response from LanceDB
Cloud.
* Implements `index_stats` for remote Rust SDK and Python async API.

nodejs/__test__/table.test.ts

@@ -479,6 +479,9 @@ describe("When creating an index", () => {
     expect(stats).toBeDefined();
     expect(stats?.numIndexedRows).toEqual(300);
     expect(stats?.numUnindexedRows).toEqual(0);
+    expect(stats?.distanceType).toBeUndefined();
+    expect(stats?.indexType).toEqual("BTREE");
+    expect(stats?.numIndices).toEqual(1);
   });
 
   test("when getting stats on non-existent index", async () => {