Add Germany Map and state flags (#4513)

Resolves #4390 

## Description:

- Adds new map, Germany, filed under the New and Europe categories, for
use in Singleplayer and Custom lobbies.
- Adds map to lobby rotation.
- Adds new flags to represent all 16 Federal German states (including a
variant of Bavaria), all to the ISO standard (DE-XX)

Map Info:
Size: 1548x1519, 2,351,412 total. 451,764 water pixels (19.2%), 826,627
impassable pixels (35.2%)
Nations: 16, all of which are Federal German States

Yes, the size has changed and also has impassable terrain added now

<img width="652" height="887" alt="image"
src="https://github.com/user-attachments/assets/6499382e-f073-4ef8-956c-4e80ef09d4b8"
/>
<img width="917" height="905" alt="image"
src="https://github.com/user-attachments/assets/d9c7a532-c2fd-415a-a51d-709be3b43aae"
/>
<img width="922" height="1140" alt="image"
src="https://github.com/user-attachments/assets/fca34d84-414c-4b3f-91ec-f0a21883caa6"
/>

## 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

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

lengy_

Sorry if I've done anything wrong or the files are out of date, I made
the map a week ago, my fork is a mess and I'm still quite new to how
exactly GitHub works.

resources/maps/germany/manifest.json

@@ -0,0 +1,120 @@
+{
+  "categories": ["europe", "new"],
+  "id": "Germany",
+  "map": {
+    "height": 1516,
+    "num_land_tiles": 1072927,
+    "width": 1548
+  },
+  "map16x": {
+    "height": 379,
+    "num_land_tiles": 64963,
+    "width": 387
+  },
+  "map4x": {
+    "height": 758,
+    "num_land_tiles": 265158,
+    "width": 774
+  },
+  "multiplayer_frequency": 5,
+  "name": "Germany",
+  "nations": [
+    {
+      "coordinates": [688, 396],
+      "flag": "DE-HH",
+      "name": "Hamburg",
+      "strength": 2
+    },
+    {
+      "coordinates": [717, 311],
+      "flag": "DE-SH",
+      "name": "Schleswig-Holstein",
+      "strength": 2
+    },
+    {
+      "coordinates": [561, 537],
+      "flag": "DE-HB",
+      "name": "Bremen",
+      "strength": 2
+    },
+    {
+      "coordinates": [399, 592],
+      "flag": "DE-NI",
+      "name": "Lower Saxony",
+      "strength": 2
+    },
+    {
+      "coordinates": [336, 803],
+      "flag": "DE-NW",
+      "name": "North Rhine-Westphalia",
+      "strength": 2
+    },
+    {
+      "coordinates": [279, 1129],
+      "flag": "DE-SL",
+      "name": "Saarland",
+      "strength": 2
+    },
+    {
+      "coordinates": [362, 1042],
+      "flag": "DE-RP",
+      "name": "Rhineland-Palatinate",
+      "strength": 2
+    },
+    {
+      "coordinates": [602, 1207],
+      "flag": "DE-BW",
+      "name": "Baden-Württemberg",
+      "strength": 2
+    },
+    {
+      "coordinates": [627, 900],
+      "flag": "DE-HE",
+      "name": "Hesse",
+      "strength": 2
+    },
+    {
+      "coordinates": [941, 1139],
+      "flag": "DE-BY-L",
+      "name": "Bavaria",
+      "strength": 2
+    },
+    {
+      "coordinates": [1077, 836],
+      "flag": "DE-SN",
+      "name": "Saxony",
+      "strength": 2
+    },
+    {
+      "coordinates": [883, 648],
+      "flag": "DE-ST",
+      "name": "Saxony-Anhalt",
+      "strength": 2
+    },
+    {
+      "coordinates": [861, 863],
+      "flag": "DE-TH",
+      "name": "Thuringia",
+      "strength": 2
+    },
+    {
+      "coordinates": [1026, 370],
+      "flag": "DE-MV",
+      "name": "Mecklenburg-Vorpommern",
+      "strength": 2
+    },
+    {
+      "coordinates": [1189, 590],
+      "flag": "DE-BE",
+      "name": "Berlin",
+      "strength": 2
+    },
+    {
+      "coordinates": [1254, 708],
+      "flag": "DE-BB",
+      "name": "Brandenburg",
+      "strength": 2
+    }
+  ],
+  "translation_key": "map.germany"
+}