Maven endpoint support (#180)

* Basic maven endpoint

* Clean up maven endpoint

* cargo sqlx prepare

* Minor cleanup

* Remove indentation

* Borrow &str instead of &String

* Refactor mod_data-getting

src/database/models/mod_item.rs

@@ -405,7 +405,7 @@ impl Mod {
     }
 
     pub async fn get_full_from_slug<'a, 'b, E>(
-        slug: String,
+        slug: &str,
         executor: E,
     ) -> Result<Option<QueryMod>, sqlx::error::Error>
     where