fix(core): Fixes various issues with codegen (#646)

- [X] Fixes bad `ReadEnum` by size
- [X] Fixes array, list, and set not handling null values properly.
  - It will be up to the user (for now) to null out empty lists using `[AfterDeserialization]`. Convenience may be added later.
- [X] Fixes errors with `dotnet clean` and non-empty generation folder
- [X] Fixes bad field indexes on `Account.cs` causing `tags` to not be serialized/deserialized.
  - This was caused by a duplicate entry. Don't have protection against this _yet_.

Projects/UOContent/Migrations/Server.Accounting.Account.v2.json

@@ -74,6 +74,15 @@
         "SerializationMethodSignatureMigrationRule"
       ]
     },
+    {
+      "name": "Tags",
+      "type": "System.Collections.Generic.List\u003CServer.Accounting.AccountTag\u003E",
+      "rule": "ListMigrationRule",
+      "ruleArguments": [
+        "Server.Accounting.AccountTag",
+        "SerializationMethodSignatureMigrationRule"
+      ]
+    },
     {
       "name": "LoginIPs",
       "type": "System.Net.IPAddress[]",