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

[joshrotenberg]

Summary

Adds --wait flag support to Cloud subscription operations, building on the foundation from #191.

Fixes #192
Part of #175

What's Changed

• ✅ Added AsyncOperationArgs to subscription Create, Update, and Delete commands
• ✅ Updated command handlers to pass async_ops parameter through the call chain
• ✅ Modified subscription_impl functions to use handle_async_response() from async_utils
• ✅ All three operations now support --wait, --wait-timeout, and --wait-interval flags

Implementation Details

This PR follows the exact same pattern established in #191:

1. Add AsyncOperationArgs via #[command(flatten)] to the CLI enum
2. Pass the parameter through command handlers
3. Replace manual task ID handling with handle_async_response() call

Testing

• Compiles successfully
• Clippy passes with no warnings
• Help text shows new flags correctly
• Manual testing with real API (requires credentials)

Example Usage

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

# Update subscription with custom timeout
redisctl cloud subscription update 123 --data @update.json --wait --wait-timeout 600

# Delete subscription with confirmation and wait
redisctl cloud subscription delete 456 --force --wait

Next Steps

After this PR, the remaining commands to update are:

• Fixed database/subscription (feat(cloud): add --wait flag to fixed database and subscription commands #193) - 8 commands
• ACL operations (feat(cloud): add --wait flag to ACL commands #194) - 9 commands
• User & provider accounts (feat(cloud): add --wait flag to user and provider account commands #195) - 4 commands
• Connectivity operations (feat(cloud): add --wait flag to connectivity commands #196) - ~20 commands