fix: built-in parser attributes link to the wrong place (#3916)

Go-to-def on `@[builtin_term_parser]` should go to the line
```lean
builtin_initialize registerBuiltinParserAttribute `builtin_term_parser ``Category.term
```
not
```lean
/-- `term` is the builtin syntax category for terms. ... -/
def term : Category := {}
```

src/Lean/Parser/Extension.lean

@@ -498,13 +498,13 @@ private def BuiltinParserAttribute.add (attrName : Name) (catName : Name)
 The parsing tables for builtin parsers are "stored" in the extracted source code.
 -/
 def registerBuiltinParserAttribute (attrName declName : Name)
-    (behavior := LeadingIdentBehavior.default) : IO Unit := do
+    (behavior := LeadingIdentBehavior.default) (ref : Name := by exact decl_name%) : IO Unit := do
   let .str ``Lean.Parser.Category s := declName
     | throw (IO.userError "`declName` should be in Lean.Parser.Category")
   let catName := Name.mkSimple s
   addBuiltinParserCategory catName declName behavior
   registerBuiltinAttribute {
-    ref             := declName
+    ref             := ref
     name            := attrName
     descr           := "Builtin parser"
     add             := fun declName stx kind => liftM $ BuiltinParserAttribute.add attrName catName declName stx kind