feat: create key in encryption service for merchant and user (#4910)

Co-authored-by: Arjun Karthik <m.arjunkarthik@gmail.com>
Co-authored-by: hyperswitch-bot[bot] <148525504+hyperswitch-bot[bot]@users.noreply.github.com>

crates/api_models/src/user.rs

@@ -379,3 +379,8 @@ pub struct AuthIdQueryParam {
 pub struct AuthSelectRequest {
     pub id: Option<String>,
 }
+
+#[derive(Debug, serde::Deserialize, serde::Serialize)]
+pub struct UserTransferKeyResponse {
+    pub total_transferred: usize,
+}