Simple Upgradable Structures (Cities, Ports, SAMs and Silos) (#1012)

## Description:

https://github.com/openfrontio/OpenFrontIO/issues/776

I've implemented upgradable structures for cities and ports.

As of right now this is just meant as a QOL change for structure
stacking that currently happens and no gameplay changes are intended.

Structure upgrades cost the same as making a new structure of that type
and function the same as making a new structure of that type.

I'm putting up a draft PR for this now since adding support for SAMs and
Silos will take more time to handle the cooldowns and I want to make
sure I'm on the right track for getting this merged.

I also still need to add bot behavior for this and re-enable min
distance for structures.

I didn't see translations for the UnitInfoModal so I've left that out
for now.

I've tested locally in a single player game so far but will document and
test more thoroughly before merging.


![image](https://github.com/user-attachments/assets/321a17cf-26a5-4152-aae1-6b6a691638bb)


![image](https://github.com/user-attachments/assets/8cfdabe6-f0a1-435a-a5a3-05b442427c2f)


## 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:

# Poutine

---------

Co-authored-by: Scott Anderson <scottanderson@users.noreply.github.com>

src/core/execution/UpgradeStructureExecution.ts

@@ -0,0 +1,44 @@
+import { Execution, Game, Player, Unit } from "../game/Game";
+
+export class UpgradeStructureExecution implements Execution {
+  private structure: Unit | undefined;
+  private cost: bigint;
+
+  constructor(
+    private player: Player,
+    private unitId: number,
+  ) {}
+
+  init(mg: Game, ticks: number): void {
+    this.structure = this.player
+      .units()
+      .find((unit) => unit.id() === this.unitId);
+
+    if (this.structure === undefined) {
+      console.warn(`structure is undefined`);
+      return;
+    }
+    if (!this.structure.info().upgradable) {
+      console.warn(`unit type ${this.structure} cannot be upgraded`);
+      return;
+    }
+    this.cost = this.structure.info().cost(this.player);
+    if (this.player.gold() < this.cost) {
+      return;
+    }
+    this.player.upgradeUnit(this.structure);
+    return;
+  }
+
+  tick(ticks: number): void {
+    return;
+  }
+
+  isActive(): boolean {
+    return false;
+  }
+
+  activeDuringSpawnPhase(): boolean {
+    return false;
+  }
+}