update runtime tok look for main in defult namespace

src/compiler/NubLang/Syntax/Tokenization/Token.cs

@@ -24,17 +24,6 @@ public enum LiteralKind
     Bool
 }
 
-public class ModifierToken(SourceSpan span, Modifier modifier) : Token(span)
-{
-    public Modifier Modifier { get; } = modifier;
-}
-
-public enum Modifier
-{
-    Extern,
-    Export
-}
-
 public class SymbolToken(SourceSpan span, Symbol symbol) : Token(span)
 {
     public Symbol Symbol { get; } = symbol;
@@ -80,5 +69,6 @@ public enum Symbol
     Calls,
     Trait,
     Impl,
-    For
+    For,
+    Extern
 }