Add Halkidiki Map (#799)

## Description:
This PR adds the Halkidiki map. It's a region in Greece with rich
history that is very popular also with tourism.

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [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:

<DISCORD USERNAME>
Nikola123

src/core/configuration/DefaultConfig.ts

@@ -131,6 +131,7 @@ export abstract class DefaultServerConfig implements ServerConfig {
           GameMapType.Asia,
           GameMapType.FalklandIslands,
           GameMapType.Baikal,
+          GameMapType.Halkidiki,
         ].includes(map)
       ) {
         return Math.random() < 0.3 ? 50 : 25;

src/core/game/Game.ts

@@ -76,6 +76,7 @@ export enum GameMapType {
   DeglaciatedAntarctica = "Deglaciated Antarctica",
   FalklandIslands = "Falkland Islands",
   Baikal = "Baikal",
+  Halkidiki = "Halkidiki",
 }
 
 export const mapCategories: Record<string, GameMapType[]> = {
@@ -101,6 +102,7 @@ export const mapCategories: Record<string, GameMapType[]> = {
     GameMapType.FaroeIslands,
     GameMapType.FalklandIslands,
     GameMapType.Baikal,
+    GameMapType.Halkidiki,
   ],
   fantasy: [
     GameMapType.Pangaea,

src/core/game/TerrainMapFileLoader.ts

@@ -46,6 +46,7 @@ const MAP_FILE_NAMES: Record<GameMapType, string> = {
   [GameMapType.EuropeClassic]: "EuropeClassic",
   [GameMapType.FalklandIslands]: "FalklandIslands",
   [GameMapType.Baikal]: "Baikal",
+  [GameMapType.Halkidiki]: "Halkidiki",
 };
 
 class GameMapLoader {