Game Version types, indexing, and bugfixes (#91)

* Add types to game_versions, allow filtering by version type

- Fixes an issue with version numbers in the initial mod indexing
  queue
- Modifies the /api/v1/categories/game_versions route to take an
  optional query parameter `type` to filter the listed game versions
- Creating tags is now idempotent
- Creating game_versions now requires a JSON body that specifies
  the version type

* Implement automatic indexing of new Minecraft versions

It's currently set to run every 6 hours and isn't configurable; we
could add config for it, but it doesn't seem likely to be rate
limited or have issues with frequency.

src/routes/mod_creation.rs

@@ -460,10 +460,10 @@ async fn mod_create_inner(
             status: status_id,
         };
 
-        let versions_list = mod_builder
+        let versions_list = mod_create_data
             .initial_versions
             .iter()
-            .flat_map(|v| v.game_versions.iter().map(|id| id.0.to_string()))
+            .flat_map(|v| v.game_versions.iter().map(|name| name.0.clone()))
             .collect::<std::collections::HashSet<String>>()
             .into_iter()
             .collect::<Vec<_>>();