implement an extension event for IPC messages coming in (#1776)

src/gui/src/IPC.js

@@ -141,6 +141,11 @@ const ipc_listener = async (event, handled) => {
         return;
     }
 
+    // --------------------------------------------------------
+    // Dispatch custom event so that extensions can listen to it
+    // --------------------------------------------------------
+    window.dispatchEvent(new CustomEvent('ipc:message', { detail: event.data }));
+
     // todo validate all event.data stuff coming from the client (e.g. event.data.message, .msg, ...)
     //-------------------------------------------------
     // READY

src/puter-js/src/modules/UI.js

@@ -765,6 +765,12 @@ class UI extends EventListener {
         })
     }
 
+    requestUpgrade = function() {
+        return new Promise((resolve) => {
+            this.#postMessageWithCallback('requestUpgrade', resolve, {  });
+        })
+    }
+
     showSaveFilePicker = function(content, suggestedName, type){
         const undefinedOnCancel = new putility.libs.promise.TeePromise();
         const resolveOnlyPromise = new Promise((resolve, reject) => {