feat(cloud): add --wait flag to subscription commands

[joshrotenberg]

Summary

Add --wait flag support to Cloud subscription operations that return task IDs, building on the foundation established in #191.

Part of #175

Background

Subscription operations are asynchronous and return task IDs. With the async_utils module now in place from #191, we can extend the --wait functionality to these commands.

Commands to Update

Subscription Operations

• cloud subscription create - Creating subscriptions
• cloud subscription update - Updating subscription configuration
• cloud subscription delete - Deleting subscriptions

Implementation Notes

1. Update CLI enum in cli.rs to add AsyncOperationArgs via #[command(flatten)]
2. Update command handlers in subscription.rs to pass async_ops parameter
3. Update implementation functions in subscription_impl.rs to use handle_async_response()
4. Follow the same pattern as database commands in feat(cloud): add --wait flag to async database operations #191

Example Usage

# Create subscription and wait for completion
redisctl cloud subscription create --data @config.json --wait

# Delete subscription with custom timeout
redisctl cloud subscription delete 123 --wait --wait-timeout 600

Acceptance Criteria

• All 3 subscription commands support --wait flag
• Progress indicators show during wait
• Timeout and interval options work correctly
• Existing behavior unchanged when --wait not specified
• Help text updated for all commands