Automatic train stations (#1353)

## Description:

Train stations are now built automatically when a factory is
constructed.

Changes:
- When a factory is built, nearby structures are connected to the rail
network
- When a city is built near a factory, it is connected to the rail
network
    - All structures behave the same when a train stops: to be defined
    - Removed station badge
    - Gold income is now related to the structure's level

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced
- [x] I understand that submitting code with bugs that could have been
caught through manual testing blocks releases and new features for all
contributors

## Please put your Discord username so you can be contacted if a bug or
regression is found:

IngloriousTom

src/server/GameServer.ts

@@ -21,7 +21,7 @@ import {
 } from "../core/Schemas";
 import { createGameRecord } from "../core/Util";
 import { GameEnv, ServerConfig } from "../core/configuration/Config";
-import { GameType, UnitType } from "../core/game/Game";
+import { GameType } from "../core/game/Game";
 import { archive } from "./Archive";
 import { Client } from "./Client";
 import { gatekeeper } from "./Gatekeeper";
@@ -222,15 +222,6 @@ export class GameServer {
               );
               return;
             }
-            if (
-              clientMsg.intent.type === "create_station" &&
-              this.gameConfig.disabledUnits?.includes(UnitType.Train)
-            ) {
-              this.log.warn(
-                `create_station is disabled, client: ${client.clientID}`,
-              );
-              return;
-            }
             this.addIntent(clientMsg.intent);
           }
           if (clientMsg.type === "ping") {