Add support for individually deprecated constructors

grammar.js

@@ -698,6 +698,7 @@ module.exports = grammar({
     data_constructors: ($) => repeat1($.data_constructor),
     data_constructor: ($) =>
       seq(
+        optional($.attribute),
         field("name", $.constructor_name),
         optional(field("arguments", $.data_constructor_arguments))
       ),

test/corpus/attributes.txt

@@ -65,3 +65,37 @@ pub fn wibble() { todo }
     parameters: (function_parameters)
     body: (block
       (todo))))
+
+================================================================================
+Individually deprecated constructors
+================================================================================
+
+pub type SomeType {
+  NotDeprecated
+  @deprecated("Please use the NotDeprecated variant")
+  Deprecated(reason: String)
+}
+
+--------------------------------------------------------------------------------
+
+(source_file
+  (type_definition
+    (visibility_modifier)
+    (type_name
+      name: (type_identifier))
+    (data_constructors
+      (data_constructor
+        name: (constructor_name))
+      (data_constructor
+        (attribute
+          name: (identifier)
+          arguments: (arguments
+            (attribute_value
+              (string
+                (quoted_content)))))
+        name: (constructor_name)
+        arguments: (data_constructor_arguments
+          (data_constructor_argument
+            label: (label)
+            value: (type
+              name: (type_identifier))))))))