PERF: Paginate loading of tags in edit nav menu tags modal (#22380)

What is the problem?

Before this change, we were relying on the  `/tags` endpoint which 
returned all the tags that are visible to a give user on the site leading to potential performance problems. 
The attribute keys of the response also changes based on the `tags_listed_by_group` site setting. 

What is the fix?

This commit fixes the problems listed above by creating a dedicate `#list` action in the
`TagsController` to handle the listing of the tags in the edit
navigation menu tags modal. This is because the `TagsController#index`
action was created specifically for the `/tags` route and the response
body does not really map well to what we need. The `TagsController#list`
action added here is also much safer since the response is paginated and
we avoid loading a whole bunch of tags upfront.

spec/system/editing_sidebar_tags_navigation_spec.rb

@@ -88,16 +88,6 @@ RSpec.describe "Editing sidebar tags navigation", type: :system do
     include_examples "a user can edit the sidebar tags navigation", true
   end
 
-  it "displays the all tags in the modal when `tags_listed_by_group` site setting is true" do
-    SiteSetting.tags_listed_by_group = true
-
-    visit "/latest"
-
-    modal = sidebar.click_edit_tags_button
-
-    expect(modal).to have_tag_checkboxes([tag1, tag2, tag3, tag4])
-  end
-
   it "allows a user to filter the tags in the modal by the tag's name" do
     visit "/latest"
 
@@ -186,4 +176,16 @@ RSpec.describe "Editing sidebar tags navigation", type: :system do
 
     expect(modal).to have_tag_checkboxes([tag1, tag2, tag3, tag4])
   end
+
+  it "loads more tags when the user scrolls views the last tag in the modal and there is more tags to load" do
+    stub_const(TagsController, "LIST_LIMIT", 2) do
+      visit "/latest"
+
+      expect(sidebar).to have_tags_section
+
+      modal = sidebar.click_edit_tags_button
+
+      expect(modal).to have_tag_checkboxes([tag1, tag2, tag3, tag4])
+    end
+  end
 end