Add missing factory in player info panel (#1507)

## Description:

The player info panel is missing the factory count. Also only displays
the units available in the current game.
 
Every unit:
<img width="185" height="238" alt="image"
src="https://github.com/user-attachments/assets/52eca7c8-99e0-4234-98d4-8efe1644a92c"
/>

City only:
<img width="186" height="142" alt="image"
src="https://github.com/user-attachments/assets/87aef9f8-697c-4aa0-8bc5-92f016886a9d"
/>


## 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 have read and accepted the CLA aggreement (only required once).

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

IngloriousTom

resources/lang/en.json

@@ -450,6 +450,7 @@
     "gold": "Gold",
     "ports": "Ports",
     "cities": "Cities",
+    "factories": "Factories",
     "missile_launchers": "Missile launchers",
     "sams": "SAMs",
     "warships": "Warships",