Normalize country code to UK instead of GB

- CountriesTool: use 'uk' key for United Kingdom
- EGFRatingsHandler: keep UK as-is (no conversion to GB)
- Pairable: convert GB to UK (inverse of previous behavior)

view-webapp/src/main/kotlin/org/jeudego/pairgoth/ratings/EGFRatingsHandler.kt

@@ -36,9 +36,6 @@ object EGFRatingsHandler: RatingsHandler(RatingsManager.Ratings.EGF) {
                                 if (adjusted < 0) "${-(adjusted - 99) / 100}k"
                                 else "${(adjusted + 100) / 100}d"
                         }
-                        if ("UK" == player.getString("country")) {
-                            player["country"] = "GB"
-                        }
                         // fix for missing firstnames
                         if (player.getString("firstname") == null) {
                             player["firstname"] = ""

view-webapp/src/main/kotlin/org/jeudego/pairgoth/view/CountriesTool.kt

@@ -95,7 +95,7 @@ class CountriesTool {
             "fj" to "Fiji",
             "fr" to "France",
             "ga" to "Gabon",
-            "gb" to "United Kingdom",
+            "uk" to "United Kingdom",
             "gd" to "Grenada",
             "ge" to "Georgia",
             "gg" to "Guernsey",