Add a volume to contain the minecraft world files

This previously didn't work because nextcloud believed we were running
http, when in reality we were running https.

Overwrite the protocol, so that nextcloud can authorize devices.

etc/nixos/services/minecraft.nix

@@ -121,6 +121,7 @@ in
         "25565:25565"
       ];
       volumes = [
+        "minecraft:/var/lib/minecraft/world"
         "${ops}:/var/lib/minecraft/ops.json:ro"
         "${whitelist}:/var/lib/minecraft/whitelist.json:ro"
       ];

etc/nixos/services/nextcloud.nix

@@ -15,6 +15,7 @@
         POSTGRES_USER = "nextcloud";
         POSTGRES_HOST = "nextcloud-postgres";
         POSTGRES_PASSWORD = "rI7t7Nek1yGA9ucrRc7Uhy0jcjwPjnXa8me4o8tJON8=";
+        OVERWRITEPROTOCOL = "https";
       };
       networks = [
         "nextcloud"