Fix subscription custom configs ignoring custom config socks port (#10296)

* Fix subscription custom configs ignoring custom config socks port

Full Xray/sing-box configs imported from a subscription no longer got the
subscription's "Custom config socks port" (SubItem.PreSocksPort) after
eff5845 and 9638b4c. 7.24.4 and earlier copied it onto every imported
config, and the Clash, Hysteria2 and raw-file paths still do.

Without it, GetPreSocksItem builds no pre-socks core for these profiles,
so they cannot be used in TUN mode. Setting the port on the profile is
not a workaround, because every subscription update re-creates the
profiles.

* Add regression test for subscription custom config socks port

v2rayN/ServiceLib/Handler/ConfigHandler.cs

@@ -1778,7 +1778,7 @@ public static class ConfigHandler
         }
         if (lstProfiles.Count > 0)
         {
-            var count = await AddBatchCustomServers(config, lstProfiles, subid, isSub);
+            var count = await AddBatchCustomServers(config, lstProfiles, subid, isSub, subItem);
             if (count > 0)
             {
                 return count;
@@ -1824,7 +1824,7 @@ public static class ConfigHandler
 
         if (lstProfiles?.Count > 0)
         {
-            var count = await AddBatchCustomServers(config, lstProfiles, subid, isSub);
+            var count = await AddBatchCustomServers(config, lstProfiles, subid, isSub, subItem);
             if (count > 0)
             {
                 return count;
@@ -1838,7 +1838,8 @@ public static class ConfigHandler
         Config config,
         List<ProfileItem> lstProfiles,
         string subid,
-        bool isSub)
+        bool isSub,
+        SubItem? subItem)
     {
         var count = 0;
         foreach (var it in lstProfiles)
@@ -1848,6 +1849,7 @@ public static class ConfigHandler
 
             if (it.ConfigType == EConfigType.Custom)
             {
+                it.PreSocksPort = subItem?.PreSocksPort;
                 if (await AddCustomServer(config, it, true) == 0)
                 {
                     count++;