Move map generator into main repo (#2006)

## Description:

Move the MapGenerator repo into OpenFrontIO so we don't need to copy
generated map files over.

## 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

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

evan

map-generator/assets/maps/mars/info.json

@@ -0,0 +1,41 @@
+{
+  "name": "Mars",
+  "nations": [
+    {
+      "coordinates": [650, 415],
+      "name": "United States",
+      "strength": 3,
+      "flag": "us"
+    },
+    {
+      "coordinates": [122, 750],
+      "name": "USSR",
+      "strength": 2,
+      "flag": "ussr"
+    },
+    {
+      "coordinates": [1232, 735],
+      "name": "Russia",
+      "strength": 2,
+      "flag": "ru"
+    },
+    {
+      "coordinates": [966, 511],
+      "name": "European Space Agency",
+      "strength": 2,
+      "flag": ""
+    },
+    {
+      "coordinates": [1460, 488],
+      "name": "United Kingdom",
+      "strength": 3,
+      "flag": "gb"
+    },
+    {
+      "coordinates": [1850, 415],
+      "name": "China",
+      "strength": 3,
+      "flag": "cn"
+    }
+  ]
+}