feat: support raw references

Author: flippette

grammar.js

@@ -1018,7 +1018,10 @@ module.exports = grammar({
 
     reference_expression: $ => prec(PREC.unary, seq(
       '&',
-      optional($.mutable_specifier),
+      choice(
+        seq('raw', choice('const', $.mutable_specifier)),
+        optional($.mutable_specifier),
+      ),
       field('value', $._expression),
     )),
 

queries/highlights.scm

@@ -121,6 +121,7 @@
 "mod" @keyword
 "move" @keyword
 "pub" @keyword
+"raw" @keyword
 "ref" @keyword
 "return" @keyword
 "static" @keyword