feat: complete memory representation gate

source/lexer/token.hon

@@ -29,6 +29,8 @@ TokenKind :: enum {
     distinct, alias
     import, test
     mut
+    c_func
+    null
 
     # literals
     ident, string
@@ -49,6 +51,7 @@ TokenKind :: enum {
 
     range, range_inclusive
     at, ampersand, caret
+    question, semicolon
     pipe
 
     # logical