[Feature Request] Support CancellationToken in all Asynchronous Methods

[EthanDelong]

Description

Currently, the asynchronous methods in the Clerk.BackendAPI project (such as Users.ListAsync) do not accept a CancellationToken.

Motivation

These tokens are necessary to prevent tasks from getting stuck on I/O operations when a task is cancelled from an external source.

Proposed Solution

1. Update the current method signatures to accept an optional CancellationToken type parameter. For example:

Task<GetUserResponse> GetAsync(string userId, RetryConfig? retryConfig = null, CancellationToken cancellationToken = default);

2. Pass the token into any inner async calls, such as HttpClient.SendAsync.

3. Call CancellationToken.ThrowIfCancellationRequested in the beginning of methods, inside loops, and prior to any heavy I/O (unless it already accepts a CT, like HttpClient).

Alternatives Considered

Using wrappers like Task.WhenAny(...) or .WaitAsync(...) to cancel the task entirely when a cancellation is requested.

Setting timeouts on the client-specific requests to prevent potential hangs.

Testing

Use a mock of the client (I think this is ISpeakEasyClient?) to fake a long-running request, and explicitly call a cancellation on our token. Ensure that it throws an OperationCanceledException.