FEATURE: Allow showing site text search in selected locale (#28453)

When searching for site texts for admin using the english
version of the text, previously we would show the english
version in the results _even if_ there was another locale
translated version available when a locale was selected
from the dropdown.

This commit adds a "Only show results in selected locale"
checkbox option which will instead make it so the results
shown are in the target locale, making it easier for translators
to tell when there is actually translations vs. missing tranlsations.

spec/system/page_objects/pages/admin_site_texts.rb

@@ -0,0 +1,53 @@
+# frozen_string_literal: true
+
+module PageObjects
+  module Pages
+    class AdminSiteTexts < PageObjects::Pages::Base
+      def visit
+        page.visit("/admin/customize/site_texts")
+        self
+      end
+
+      def search(text)
+        find(".site-text-search").fill_in(with: text)
+        page.send_keys(:escape)
+      end
+
+      def has_translation_key?(key)
+        has_css?(".site-text-id", text: key)
+      end
+
+      def has_translation_value?(value)
+        has_css?(".site-text-value", text: value)
+      end
+
+      def select_locale(locale_short_name)
+        locale_selector = PageObjects::Components::SelectKit.new(".locale-search")
+        locale_selector.expand
+        locale_selector.select_row_by_value(locale_short_name)
+        locale_selector.collapse
+      end
+
+      def toggle_only_show_overridden
+        find("#toggle-overridden").click
+      end
+
+      def toggle_only_show_outdated
+        find("#toggle-outdated").click
+      end
+
+      def toggle_only_show_results_in_selected_locale
+        find("#toggle-only-locale").click
+      end
+
+      def edit_translation(key)
+        find(".site-text[data-site-text-id='#{key}']").find(".site-text-edit").click
+      end
+
+      def override_translation(value)
+        find(".site-text-value").fill_in(with: value)
+        find(".save-changes").click
+      end
+    end
+  end
+end