Add ECH config support to profile and UI

Introduces EchConfigList and EchForceQuery fields to ProfileItem and V2rayConfig models, updates related handlers and services to process these fields, and extends the AddServerWindow UI to allow user input for ECH configuration. Also adds localization entries for the new fields and updates extension methods for string handling.

v2rayN/ServiceLib/Handler/Fmt/BaseFmt.cs

@@ -70,6 +70,10 @@ public class BaseFmt
             }
             ToUriQueryAllowInsecure(item, ref dicQuery);
         }
+        if (item.EchConfigList.IsNotEmpty())
+        {
+            dicQuery.Add("ech", Utils.UrlEncode(item.EchConfigList));
+        }
 
         dicQuery.Add("type", item.Network.IsNotEmpty() ? item.Network : nameof(ETransport.tcp));
 
@@ -209,6 +213,7 @@ public class BaseFmt
         item.ShortId = GetQueryDecoded(query, "sid");
         item.SpiderX = GetQueryDecoded(query, "spx");
         item.Mldsa65Verify = GetQueryDecoded(query, "pqv");
+        item.EchConfigList = GetQueryDecoded(query, "ech");
 
         if (_allowInsecureArray.Any(k => GetQueryDecoded(query, k) == "1"))
         {