Reduce code execution in DetailsPresenter

This presenter currently performs some of the same code in different
methods that determine the type of content in the field, and looks for
content types even when we know there won't be any present.

Therefore refactoring this presenter to perform as little code execution
as possible to order to determine the correct outcome for the content
type given.

This performance improvement is particularly important for GraphQL, as
we will be converting govspeak to HTML at render-time.

app/presenters/details_presenter.rb

@@ -22,29 +22,30 @@ def details
 
   private
 
-    def govspeak_content?(value)
-      wrapped = Array.wrap(value)
-      wrapped.all? { |hsh| hsh.is_a?(Hash) } &&
-        wrapped.one? { |hsh| hsh[:content_type] == "text/govspeak" } &&
-        wrapped.none? { |hsh| hsh[:content_type] == "text/html" }
-    end
-
-    def html_content?(value)
-      wrapped = Array.wrap(value)
-      wrapped.all? { |hsh| hsh.is_a?(Hash) } &&
-        wrapped.one? { |hsh| hsh[:content_type] == "text/html" }
+    def content_type(value)
+      if value.one? { |hsh| hsh[:content_type] == "text/html" }
+        "text/html"
+      elsif value.one? { |hsh| hsh[:content_type] == "text/govspeak" }
+        "text/govspeak"
+      end
     end
 
     def recursively_transform_govspeak(obj)
-      return obj if !obj.respond_to?(:map) || html_content?(obj)
-      return render_govspeak(obj) if govspeak_content?(obj)
-
-      if obj.is_a?(Hash)
+      if obj.is_a?(Array) && obj.all?(Hash) && (obj_content_type = content_type(obj))
+        case obj_content_type
+        when "text/html"
+          obj
+        when "text/govspeak"
+          render_govspeak(obj)
+        end
+      elsif obj.is_a?(Array)
+        obj.map { |o| recursively_transform_govspeak(o) }
+      elsif obj.is_a?(Hash)
         obj.transform_values do |value|
           recursively_transform_govspeak(value)
         end
       else
-        obj.map { |o| recursively_transform_govspeak(o) }
+        obj
       end
     end