Refactor UnitSpecific info => AllUnitParams type union (#701)

## Description:

By using a type union we get better type safety, enforcing each unit
type have the appropriate params when initializing

## 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:
evan

---------

Co-authored-by: evan <openfrontio@gmail.com>

src/core/execution/CityExecution.ts

@@ -38,7 +38,7 @@ export class CityExecution implements Execution {
         this.active = false;
         return;
       }
-      this.city = this.player.buildUnit(UnitType.City, 0, spawnTile);
+      this.city = this.player.buildUnit(UnitType.City, spawnTile, {});
     }
     if (!this.city.isActive()) {
       this.active = false;