DEV: Introduce history-store service (#24486)

This commit extracts the storage part of the route-scroll-manager into a dedicated service. This provides a key/value store which will reset for each navigation, and restore previous values when the user uses the back/forward buttons in their browser.

This gives us a reliable replacement for the old `DiscourseRoute.isPoppedState` function, which would not work under all situations.

Previously reverted in e6370decfdcb87737e76b21fe1bbe033af08afaa. This version has been significantly refactored, and includes an additional system spec for the issue we identified.

spec/system/topic_list_focus_spec.rb

@@ -81,4 +81,26 @@ describe "Topic list focus", type: :system do
     expect(page).to have_css("body.navigation-topics")
     expect(focussed_topic_id).to eq(nil)
   end
+
+  it "refocusses properly when there are multiple pages of topics" do
+    extra_topics = Fabricate.times(25, :post).map(&:topic)
+    oldest_topic = Fabricate(:post).topic
+    oldest_topic.update(bumped_at: 1.day.ago)
+
+    visit("/latest")
+
+    # Scroll to bottom for infinite load
+    page.execute_script <<~JS
+      document.querySelectorAll('.topic-list-item')[24].scrollIntoView(true);
+    JS
+
+    # Click a topic
+    discovery.topic_list.visit_topic(oldest_topic)
+    expect(topic).to have_topic_title(oldest_topic.title)
+
+    # Going back to the topic-list should re-focus
+    page.go_back
+    expect(page).to have_css("body.navigation-topics")
+    expect(focussed_topic_id).to eq(oldest_topic.id)
+  end
 end