upgrade unit when building a unit of same type (#1328)

## Description:

When building a structure in the same location as a nearby structure, it
will update the existing structure instead of creating a new one.

Also fix ctrl+click shortcut to bring up the build menu.

## 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/PlayerImpl.test.ts

@@ -0,0 +1,48 @@
+import {
+  Game,
+  Player,
+  PlayerInfo,
+  PlayerType,
+  UnitType,
+} from "../src/core/game/Game";
+import { setup } from "./util/Setup";
+
+let game: Game;
+let player: Player;
+
+describe("PlayerImpl", () => {
+  beforeEach(async () => {
+    game = await setup(
+      "plains",
+      {
+        infiniteGold: true,
+        instantBuild: true,
+      },
+      [new PlayerInfo("player", PlayerType.Human, null, "player_id")],
+    );
+
+    while (game.inSpawnPhase()) {
+      game.executeNextTick();
+    }
+
+    player = game.player("player_id");
+  });
+
+  test("City can be upgraded", () => {
+    const city = player.buildUnit(UnitType.City, game.ref(0, 0), {});
+    const buCity = player
+      .buildableUnits(game.ref(0, 0))
+      .find((bu) => bu.type === UnitType.City);
+    expect(buCity).toBeDefined();
+    expect(buCity!.canUpgrade).toBe(city.id());
+  });
+
+  test("DefensePost cannot be upgraded", () => {
+    player.buildUnit(UnitType.DefensePost, game.ref(0, 0), {});
+    const buDefensePost = player
+      .buildableUnits(game.ref(0, 0))
+      .find((bu) => bu.type === UnitType.DefensePost);
+    expect(buDefensePost).toBeDefined();
+    expect(buDefensePost!.canUpgrade).toBeFalsy();
+  });
+});