feat(events): add hashed customer_email and feature_metadata (#5220)

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

crates/common_utils/src/hashing.rs

@@ -0,0 +1,22 @@
+use masking::{PeekInterface, Secret, Strategy};
+use serde::{Deserialize, Serialize, Serializer};
+
+#[derive(Clone, Debug, Deserialize)]
+/// Represents a hashed string using blake3's hashing strategy.
+pub struct HashedString<T: Strategy<String>>(Secret<String, T>);
+
+impl<T: Strategy<String>> Serialize for HashedString<T> {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        let hashed_value = blake3::hash(self.0.peek().as_bytes()).to_hex();
+        hashed_value.serialize(serializer)
+    }
+}
+
+impl<T: Strategy<String>> From<Secret<String, T>> for HashedString<T> {
+    fn from(value: Secret<String, T>) -> Self {
+        Self(value)
+    }
+}