improve project dialog system

- project model : refactor getSteps() method
- create dialog store
- create DialogWrapper component that open the dialog corresponding to the URL query param

public/site/templates/dialog.json.php

@@ -0,0 +1,13 @@
+<?php
+
+$specificData = [
+  // "exampleField" => $page->exampleField(),
+  // "exampleHardData" => 'Example hard value'
+];
+
+$pageData = array_merge($genericData, $specificData);
+
+echo json_encode([
+  "page" => $pageData,
+  "user" => $userData
+]);