refactor(customer): refactor customer db with storage utils and move trait to domain_models and impl to storage_model (#7538)

Co-authored-by: hyperswitch-bot[bot] <148525504+hyperswitch-bot[bot]@users.noreply.github.com>

crates/router/src/db.rs

@@ -96,7 +96,7 @@ pub trait StorageInterface:
     + blocklist_lookup::BlocklistLookupInterface
     + configs::ConfigInterface
     + capture::CaptureInterface
-    + customers::CustomerInterface
+    + customers::CustomerInterface<Error = StorageError>
     + dashboard_metadata::DashboardMetadataInterface
     + dispute::DisputeInterface
     + ephemeral_key::EphemeralKeyInterface

crates/router/src/db/kafka_store.rs

@@ -372,6 +372,7 @@ impl ConfigInterface for KafkaStore {
 
 #[async_trait::async_trait]
 impl CustomerInterface for KafkaStore {
+    type Error = errors::StorageError;
     #[cfg(all(any(feature = "v1", feature = "v2"), not(feature = "customer_v2")))]
     async fn delete_customer_by_customer_id_merchant_id(
         &self,