refactor: rename empty_type to never_type

Author: amaanq

grammar.js

@@ -708,7 +708,7 @@ module.exports = grammar({
       $.function_type,
       $._type_identifier,
       $.macro_invocation,
-      $.empty_type,
+      $.never_type,
       $.dynamic_type,
       $.bounded_type,
       alias(choice(...primitiveTypes), $.primitive_type),
@@ -843,7 +843,7 @@ module.exports = grammar({
       field('type', $._type),
     ),
 
-    empty_type: _ => '!',
+    never_type: _ => '!',
 
     abstract_type: $ => seq(
       'impl',

test/corpus/declarations.txt

@@ -278,7 +278,7 @@ fn aborts() -> ! {
   (function_item
     (identifier)
     (parameters)
-    (empty_type)
+    (never_type)
     (block)))
 
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