Fix the parser issue for not recognize Generic<T>[N] (#5912)

Close #5911.

In this issue, if we define the generic in source file 1,
and import it into source file 2, then when parsing the
reference of that generic in source file 2, we will not parse
the generic directly, instead we have a logic to speculate it
as generics first with a fake diagnostic sink, and if there is
no error report, we will consider it as a actual generic and will
parse it again.

In this logic, we will also disambiguate the expression based on
the following token, but we didn't consider the token '[', so we
will finally not treat the expression as generic.

The fix is just simply add '[' here.

Co-authored-by: Yong He <yonghe@outlook.com>

Author: kaizhangNV

source/slang/slang-parser.cpp

@@ -2335,6 +2335,7 @@ static Expr* tryParseGenericApp(Parser* parser, Expr* base)
         case TokenType::Dot:
         case TokenType::LParent:
         case TokenType::RParent:
+        case TokenType::LBracket:
         case TokenType::RBracket:
         case TokenType::Colon:
         case TokenType::Comma: