[APP-775] Add Welcome screen after account creation (#1038)

* add comments to step 1-3

* add onboarding screen

* add analytics for onboarding tracking

* fix useEffect

* change text

* change icon size

* put onboarding into bottom sheet modal instead of react navigation

* wip

* Simplify the type validation

* Fix: only trigger onboarding modal when account creation succeeds

* Add the 'session-ready' event which fires when the new session is stable

* Use the 'session-ready' event to trigger the onboarding modal

* update copy

* update copy

---------

Co-authored-by: Paul Frazee <pfrazee@gmail.com>

src/state/models/root-store.ts

@@ -135,8 +135,9 @@ export class RootStoreModel {
     /* dont await */ this.preferences.sync()
     await this.me.load()
     if (!hadSession) {
-      resetNavigation()
+      await resetNavigation()
     }
+    this.emitSessionReady()
   }
 
   /**
@@ -195,6 +196,14 @@ export class RootStoreModel {
     DeviceEventEmitter.emit('session-loaded')
   }
 
+  // the session has completed all setup; good for post-initialization behaviors like triggering modals
+  onSessionReady(handler: () => void): EmitterSubscription {
+    return DeviceEventEmitter.addListener('session-ready', handler)
+  }
+  emitSessionReady() {
+    DeviceEventEmitter.emit('session-ready')
+  }
+
   // the session was dropped due to bad/expired refresh tokens
   onSessionDropped(handler: () => void): EmitterSubscription {
     return DeviceEventEmitter.addListener('session-dropped', handler)