`BulkAllRequestDescriptor` does not have an implicit conversion operator to cast to `BulkAllRequest`

[TCTroyBrown]

Elastic.Clients.Elasticsearch version: 9.1.5

Elasticsearch version: 9+

Description of the problem including expected versus actual behavior:
BulkAllRequestDescriptor does not have an implicit conversion operator to cast to BulkAllRequest. So we cannot use the descriptor within the BulkAll call directly. We have to manually create a BulkAllRequest,

Expected behavior
This should be allowed

Client.BulkAll(new BulkAllRequestDescriptor());