Initial prototype of the V3 manifest extension (#4357)

* Initial prototype of the V3 manifest extension

* Make sure the content script is only injected once

* Implement addNote button

* More separation work for tasks, implement archive and update note

* Add back missing functionality, add guide to install Extensions

* Revert v2 changes

---------

Co-authored-by: Thomas Rogers <Podginator@gmail.com>

pkg/extension-v3/src/window.d.ts

@@ -0,0 +1,12 @@
+export {}
+
+declare type AndroidWebKitMessenger = {
+  // 1st argument is an actionID value, 2nd is jsonString
+  handleIdentifiableMessage: (string, string) => void
+}
+
+declare global {
+  interface Window {
+    showToolbar?: (payload: { type: string }) => void
+  }
+}