DEV: Allow typed objects theme settings to be saved via settings editor (#26100)

Why this change?

On the `/admin/customize/themes/<:id>` route, we allow admins to edit
all settings via a settings editor. Prior to this change, trying to edit
and save a typed objects theme settings will result in an error on the
server.

spec/system/page_objects/components/ace_editor.rb

@@ -9,6 +9,9 @@ module PageObjects
       end
 
       def fill_input(content)
+        # Clear the input before filling it in because capybara's fill_in method doesn't seem to replace existing content
+        # unless the content is a blank string.
+        editor_input.fill_in(with: "")
         editor_input.fill_in(with: content)
         self
       end
@@ -18,7 +21,10 @@ module PageObjects
       end
 
       def editor_input
-        find(".ace-wrapper .ace_text-input", visible: false)
+        find(".ace-wrapper .ace:not(.hidden)", visible: true).find(
+          ".ace_text-input",
+          visible: false,
+        )
       end
     end
   end

spec/system/page_objects/components/admin_theme_settings_editor.rb

@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+module PageObjects
+  module Components
+    class AdminThemeSettingsEditor < Base
+      def fill_in(settings)
+        editor.fill_input(settings)
+        self
+      end
+
+      def save
+        click_button(I18n.t("admin_js.admin.customize.theme.save"))
+        self
+      end
+
+      private
+
+      def editor
+        @editor ||= within(".settings-editor") { AceEditor.new }
+      end
+    end
+  end
+end

spec/system/page_objects/pages/admin_customize_themes.rb

@@ -42,6 +42,11 @@ module PageObjects
       def click_edit_objects_theme_setting_button(setting_name)
         find(".theme-setting[data-setting=\"#{setting_name}\"] .setting-value-edit-button").click
       end
+
+      def click_theme_settings_editor_button
+        click_button(I18n.t("admin_js.admin.customize.theme.settings_editor"))
+        PageObjects::Components::AdminThemeSettingsEditor.new
+      end
     end
   end
 end