Moddable victories (#6161)

* Added a moddable (but not yet functional) file for victories

* Spaceship parts are units now

* Fixed tests

* Added milestone objects

* Made 'our status' table in VictoryScreen dependend on file

* Updated VictoryManager to use the new Milestone system

* Fixed bug where in vanilla too many spaceship parts could beb uild

* Whoops

* Updated global victory table to use the jsons

* Updated the new game screen to show the new victory types
Also started with the deprecation of VictorType

* Did some translation stuff, also finally fixed the tests

* Removed VictoryType and reworked AI to use Milestones instead

* Add some checks for the victory file; tested that custom victories work
Also moves some code to a better spot and fixes compilation errors

* Fixed some things I thought about while falling asleep
Most notably: built -> build; fixed spaceship part construction 
priority; removed more code for the old system

* Fixed translation issues on the victory screen

core/src/com/unciv/Constants.kt

@@ -47,9 +47,11 @@ object Constants {
     const val citadel = "Citadel"
 
     const val futureTech = "Future Tech"
-    // Easter egg name. Hopefully is to hopefully avoid conflicts when later players can name their own religions.
+    // Easter egg name. Is to avoid conflicts when players name their own religions.
     // This religion name should never be displayed.
     const val noReligionName = "The religion of TheLegend27"
+    
+    const val neutralVictoryType = "Neutral"
 
     const val cancelImprovementOrder = "Cancel improvement order"
     const val tutorialPopupNamePrefix = "Tutorial: "