Add Polling Client for Async APIs

[fern-bot]

Adds a polling client that works with both asynchronous and synchronous APIs. It operates under the following conditions:

• If the response specifies a header Location or the body contains a statusUrl, this url is extracted and polled for 30 seconds or until a completed or failed status is received.
• If there is an unexpected failure in the first call, the error is returned.
• If there is an unexpected failure in the second call, the error is returned.