graphql: add missing highlights

* enum values
* comment
* input parameters
* 'implements' keyword
* include '@' in directive name
* fragment definition and spread

queries/graphql/highlights.scm

@@ -22,6 +22,9 @@
 (directive_definition
   (name) @type)
 
+(directive_definition
+  "@" @type)
+
 (scalar_type_extension
   (name) @type)
 
@@ -62,12 +65,22 @@
   (object_field
     (name) @property))
 
+(enum_value
+  (name) @property)
+
 ; Variable Definitions and Arguments 
 ;-----------------------------------
 
 (operation_definition
   (name) @variable)
 
+(fragment_name
+  (name) @variable)
+
+(input_fields_definition
+  (input_value_definition
+    (name) @parameter))
+
 (argument
   (name) @parameter)
 
@@ -125,6 +138,7 @@
   "schema"
   "on"
   "repeatable"
+  "implements"
 ] @keyword
 
 ; Punctuation
@@ -147,4 +161,3 @@
 
 "..." @punctuation.special
 "!" @punctuation.special
-