feat(admin): Add pages index Stimulus controller

This controller provides a openModal action that we can use to load
the modal remotely instead of returning the whole index page with
the table rendered below the modal.

Currently no page uses this, but it can be implemented page by page.

admin/app/components/solidus_admin/layout/page_helpers.rb

@@ -2,7 +2,7 @@
 
 module SolidusAdmin::Layout::PageHelpers
   def page(**attrs, &block)
-    tag.div(capture(&block), class: "px-4 relative", "data-controller": stimulus_id, **attrs) +
+    tag.div(capture(&block), class: "px-4 relative", "data-controller": attrs.fetch(:stimulus_id, stimulus_id), **attrs) +
       tag.div(render(component("layout/feedback").new), class: "flex justify-center py-10")
   end
 

admin/app/components/solidus_admin/ui/pages/index/component.html.erb

@@ -1,4 +1,4 @@
-<%= page do %>
+<%= page "data-controller": stimulus_id do %>
   <% if @tabs %>
     <%= page_header do %>
       <%= render_title %>

admin/app/components/solidus_admin/ui/pages/index/component.js

@@ -0,0 +1,10 @@
+import { Controller } from "@hotwired/stimulus";
+
+export default class extends Controller {
+  async openModal(event) {
+    event.preventDefault();
+    const url = event.target.href;
+    const response = await fetch(url);
+    document.body.insertAdjacentHTML("beforeend", await response.text());
+  }
+}

admin/app/components/solidus_admin/ui/pages/index/component.rb

@@ -20,6 +20,10 @@ def scopes; []; end
   def filters; []; end
   def columns; []; end
 
+  def self.stimulus_id
+    "ui--pages--index"
+  end
+
   def initialize(page:)
     @page = page
     @tabs = tabs&.map { |tab| Tab.new(**tab) }