refactor: Remove duplicate imports and comment out rate limiter implementation in charging-engine

- Remove duplicate CreditManager and RatingPlansRepo imports from engine.rs
- Add circuit_breaker module to main.rs imports
- Comment out rate_limit module in lib.rs
- Update rate_limit.rs imports to use GovernorConfig and GovernorLayer directly
- Change GovernorConfigBuilder to GovernorConfig::builder() and update config initialization
- Update GovernorLayer::new() to take config reference

apps/charging-engine/src/lib.rs

@@ -1,7 +1,8 @@
 pub mod auth;
 pub mod charging;
 pub mod circuit_breaker;
-pub mod rate_limit;
+pub mod errors;
+// pub mod rate_limit;
 pub mod handlers;
 pub mod routes;
 pub mod models;