[Android] Persistent Mobile Notifications / Inbox

[nizmaylova]

Goal

Supporting improved course navigation for mobile learners to support sequence based learning progressions in courses, and top level navigation cleanup as well.

Slack: #wg-product-mobile
Requirement Definition: Confluence Project Page

### Tasks
- [ ] https://github.com/openedx/openedx-app-android/issues/120
- [ ] https://github.com/openedx/openedx-app-android/issues/121
- [ ] https://github.com/openedx/openedx-app-android/issues/122

[marcotuts]

Product design / definition is completed and reflected in the confluence page.

[edschema]

Closing to move to the new wg-mobile repo; platform agnostic repo to hold epics/stories