Add multi-player and remote bridge support

src/web/views/signage/slides/popup-preview.hbs

@@ -58,6 +58,12 @@
   <div class="slide-preview-popup-canvas" id="popup-preview-canvas"></div>
 </div>
 
+{{#if popupPreviewPayloadJson}}
+<script>
+  window.__pulsePopupPreviewPayload = {{{popupPreviewPayloadJson}}};
+</script>
+{{/if}}
+
 <script>
   (function () {
     function startPreviewVideoPlayback(root) {
@@ -127,6 +133,10 @@
     var canvas = document.getElementById('popup-preview-canvas');
 
     function readPayload() {
+      if (window.__pulsePopupPreviewPayload) {
+        return window.__pulsePopupPreviewPayload;
+      }
+
       var hash = String(window.location.hash || '').replace(/^#/, '');
       if (!hash) {
         return null;