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/configuration/DefaultConfig.ts

@@ -347,6 +347,7 @@ export class DefaultConfig implements Config {
                 ),
           territoryBound: true,
           constructionDuration: this.instantBuild() ? 0 : 2 * 10,
+          upgradable: true,
         };
       case UnitType.AtomBomb:
         return {
@@ -390,6 +391,7 @@ export class DefaultConfig implements Config {
               : 1_000_000n,
           territoryBound: true,
           constructionDuration: this.instantBuild() ? 0 : 10 * 10,
+          upgradable: true,
         };
       case UnitType.DefensePost:
         return {
@@ -406,6 +408,7 @@ export class DefaultConfig implements Config {
                 ),
           territoryBound: true,
           constructionDuration: this.instantBuild() ? 0 : 5 * 10,
+          upgradable: true,
         };
       case UnitType.SAMLauncher:
         return {
@@ -422,6 +425,7 @@ export class DefaultConfig implements Config {
                 ),
           territoryBound: true,
           constructionDuration: this.instantBuild() ? 0 : 30 * 10,
+          upgradable: true,
         };
       case UnitType.City:
         return {
@@ -439,6 +443,7 @@ export class DefaultConfig implements Config {
                 ),
           territoryBound: true,
           constructionDuration: this.instantBuild() ? 0 : 2 * 10,
+          upgradable: true,
         };
       case UnitType.Construction:
         return {
@@ -666,7 +671,11 @@ export class DefaultConfig implements Config {
       player.type() === PlayerType.Human && this.infiniteTroops()
         ? 1_000_000_000
         : 2 * (Math.pow(player.numTilesOwned(), 0.6) * 1000 + 50000) +
-          player.units(UnitType.City).length * this.cityPopulationIncrease();
+          player
+            .units(UnitType.City)
+            .map((city) => city.level())
+            .reduce((a, b) => a + b, 0) *
+            this.cityPopulationIncrease();
 
     if (player.type() === PlayerType.Bot) {
       return maxPop / 2;
@@ -761,8 +770,7 @@ export class DefaultConfig implements Config {
   }
 
   structureMinDist(): number {
-    // TODO: Increase this to ~15 once upgradable structures are implemented.
-    return 1;
+    return 15;
   }
 
   shellLifetime(): number {