Support for idempotent requests

[cvanderschuere]

Docs: https://developer.zendesk.com/api-reference/ticketing/introduction/#idempotency

With the current API client, there doesn't seem to be a way to specify an idempotent key on specific requests

[snatchblock]

Thank you Chris. We will take this as a feature to add to the SDK.

[mcampbellsb]

FWIW, I would like to +1 this feature request.