[bug]: Return type mismatches in SearchClient

### Description

The following error is shown here only as an example for the `deleteIndex` method. It also affects all other methods, as far as I can see.

According to PHPDoc, `deleteIndex` returns `array|DeletedAtResponse`, but in fact `sendRequest` returns the response of the `handleResponse` method (ApiWrapper.php), which is an `array` and not an object. Therefore, the `deleteIndex` method never returns the described object of type `DeletedAtResponse`, making it impossible to call `valid`, for example, to check whether the response was successful or not.

### Client

Search

### Version

latest

### Relevant log output

```shell

```