Silently log ranking stats for each major civ every turn (#8964)

* Record each stat each round for each civilization.

* Implement custom serialization and encapsulate logic in separate CivRankingHistory.kt

* Address comments

* Address comments and add RankingTypeTest.kt

tests/src/com/unciv/ui/screens/victoryscreen/RankingTypeTest.kt

@@ -0,0 +1,22 @@
+package com.unciv.ui.screens.victoryscreen
+
+import com.unciv.testing.GdxTestRunner
+import org.junit.Assert
+import org.junit.Test
+import org.junit.runner.RunWith
+
+@RunWith(GdxTestRunner::class)
+class RankingTypeTests {
+
+    @Test
+    fun checkIdForSerializationUniqueness() {
+        val uniqueIds = HashSet<String>()
+        for (rankingType in RankingType.values()) {
+            val id = rankingType.idForSerialization
+            Assert.assertTrue(
+                "Id $id for RankingType $rankingType is not unique",
+                uniqueIds.add(id)
+            )
+        }
+    }
+}