unified: drop element field on _parenthesized_type

Same pattern we've seen many times before: a field on an anonymous node
gets attached to the parent node instead.

I'm not 100% sure this is the right solution, but it seemed wrong to
just make `_parenthesized_type` named instead (we don't usually name
parentheticals). At the very least, this cleans up the spurious
navigation_expression.element and tuple_type_item.element fields.

unified/extractor/tree-sitter-swift/grammar.js

@@ -567,10 +567,7 @@ module.exports = grammar({
     _parenthesized_type: ($) =>
       seq(
         "(",
-        field(
-          "element",
-          choice($.opaque_type, $.existential_type, $.dictionary_type)
-        ),
+        choice($.opaque_type, $.existential_type, $.dictionary_type),
         ")"
       ),
     navigation_expression: ($) =>

unified/extractor/tree-sitter-swift/node-types.yml

@@ -314,7 +314,6 @@ named:
     rhs: expression
   mutation_modifier:
   navigation_expression:
-    element?: [dictionary_type, existential_type, opaque_type]
     suffix: navigation_suffix
     target+: ["(", ")", array_type, dictionary_type, existential_type, expression, opaque_type, user_type]
   navigation_suffix:
@@ -459,8 +458,7 @@ named:
     $children?: tuple_type_item
     element*: tuple_type_item
   tuple_type_item:
-    $children*: [parameter_modifiers, wildcard_pattern]
-    element?: [dictionary_type, existential_type, opaque_type]
+    $children*: [dictionary_type, existential_type, opaque_type, parameter_modifiers, wildcard_pattern]
     name?: simple_identifier
     type?: type
   type: