[SwiftSyntax] Add kind and self.element_name

Author: kimdv

utils/gyb_syntax_support/Node.py

@@ -21,8 +21,10 @@ def __init__(self, name, description=None, kind=None, traits=None,
                  element_choices=None, omit_when_empty=False, 
                  elements_separated_by_newline=False):
         self.syntax_kind = name
+        self.element_name = element_name
         self.swift_syntax_kind = lowercase_first_word(name)
         self.name = kind_to_type(self.syntax_kind)
+        self.kind = kind
         self.description = description
 
         self.traits = traits or []