Factory spawns trains (#1408)

## Description:

- Change trains so it spawns from factories only
- Increase train frequency as they will now spawn from a single
structure.
- Factory will spawn more trains depending on its level
- Fix port to connect to nearby railroads
- Add factory description

## 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

---------

Co-authored-by: Tom Rouillard <trouilla@mathworks.com>
Co-authored-by: evanpelle <evanpelle@gmail.com>

src/core/game/TrainStation.ts

@@ -45,20 +45,13 @@ class PortStopHandler implements TrainStopHandler {
 }
 
 class FactoryStopHandler implements TrainStopHandler {
+  private factor: bigint = BigInt(2);
   onStop(
     mg: Game,
     station: TrainStation,
     trainExecution: TrainExecution,
   ): void {
-    const goldBonus = mg.config().trainGold();
-    station.unit.owner().addGold(goldBonus);
-    mg.addUpdate({
-      type: GameUpdateType.BonusEvent,
-      tile: station.tile(),
-      gold: Number(goldBonus),
-      workers: 0,
-      troops: 0,
-    });
+    station.unit.owner().addGold(mg.config().trainGold(), station.tile());
   }
 }