feat: add test-support feature for consumer testing (#43)

Add a new test-support feature that provides mock server utilities
and fixtures for testing code that uses the redis-cloud client library.

The testing module includes:
- MockCloudServer: A pre-configured mock server wrapper around wiremock
  with convenience methods for common Redis Cloud API endpoints
- Fixtures: Builder-pattern fixtures for Subscription, Database, Task,
  Account, and User responses
- Response helpers: Convenience functions for creating success and error
  HTTP responses (success, created, accepted, not_found, rate_limited, etc.)

Consumers can enable this with:
  redis-cloud = { version = "0.8", features = ["test-support"] }

This mirrors the test-support feature already available in redis-enterprise.

Author: joshrotenberg

Cargo.toml

@@ -33,6 +33,11 @@ futures-core = "0.3"
 
 [features]
 tower-integration = ["tower"]
+test-support = ["wiremock"]
+
+[dependencies.wiremock]
+version = "0.6"
+optional = true
 
 [dev-dependencies]
 wiremock = "0.6"

src/lib.rs

@@ -295,6 +295,10 @@ pub use error::{CloudError, Result};
 #[cfg(feature = "tower-integration")]
 pub use client::tower_support;
 
+// Test support module - only available with test-support feature
+#[cfg(feature = "test-support")]
+pub mod testing;
+
 // Types module for shared models
 pub mod types;