Move map metadata to map manifest (#1262)

## Description:

To simply the map binary data, remove height & width data to the
manifest

## 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:
evan

tests/testdata/maps/plains/manifest.json

@@ -0,0 +1,13 @@
+{
+  "map": {
+    "height": 100,
+    "num_land_tiles": 10000,
+    "width": 100
+  },
+  "mini_map": {
+    "height": 50,
+    "num_land_tiles": 2500,
+    "width": 50
+  },
+  "name": "Plains"
+}