feat: add get_digest_type_meta function to format digest type as lowercase string

src/digest_engine.rs

@@ -83,3 +83,7 @@ pub fn default_digest_type() -> DigestType {
     }
     default
 }
+
+pub fn get_digest_type_meta(digest_type: DigestType) -> String {
+    format!("digest_{}", digest_type.to_string().to_lowercase())
+}