feat: Enhance API macros with documentation support and stronger typing - Queue

[cl11e]

Description

This PR introduces significant improvements to API client macros, adding documentation support and more robust type generation while maintaining backward compatibility.

Impact:

• Self-documenting API endpoints
• Reduced boilerplate for result types
• Better IDE support via visible docs
• More maintainable client code

Documented Macro Inputs

1. api_endpoint!

• Endpoint struct with lifetime parameters
• EndpointSpec trait implementation
• Proper HTTP method binding
• Path formatting with variables
• Request body serialization (when needed)
• Added support for /// doc comments in api_endpoint!
• Preserves documentation on generated structs

api_endpoint!(
    /// Acknowledge + Retry messages from a Queue.
    /// <https://developers.cloudflare.com/api/resources/queues/subresources/messages/methods/ack/>
    POST,
    AckRetry => AckQueueResults,
    "accounts/{}/queues/{}/messages/ack";
    account_id,
    queue_id;
    params: ActionMessage
);

2. api_results!

• Generates a {Name}Results struct that encapsulates the typed payload within the results field of an ApiResponse wrapper.
• Dedicated macro for result type generation
• Supports field-level documentation
• Enforces snake_case serialization

// gen `AckQueueResults`
api_results!(AckQueue {
    /// The number of messages that were succesfully acknowledged.
    ackCount: u64,
    /// The number of messages that were succesfully retried.
    retryCount: u64,
    warnings: Vec<String>,
});
// gen `PullQueueResults`
api_results!(PullQueue {
    id: String,
    attempts: i64,
    body: String,
    /// An ID that represents an "in-flight" message that has been pulled from a Queue. You must hold on to this ID and use it to acknowledge this message.
    lease_id: String,
});

3. api_gen!

• macro that generates trivial trait implementations for ApiResult

api_gen!(PullQueueResults);