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.
Note this currently the filter/where is only implemented for LocalTable
so that it requires an explicit cast to "enable" (see new unit test).
The alternative is to add it to the Table interface, but since it's not
available on RemoteTable this may cause some user experience issues.
