[Research] [Dashboard plugin De-Angular] Breakdown of the angular dashboard app controller

[abbyhu2000]

https://github.com/opensearch-project/OpenSearch-Dashboards/blob/main/src/plugins/dashboard/public/application/dashboard_app_controller.tsx
In the current angular implementation of the dashboard plugin, the dashboard app controller contains most of the important logics including state management/global sync+app sync, embeddable and embeddable container logics, top navigation bar logics, panel nav actions, rendering of the dashboard editor.

Understand and document the logics in the controller will help de-angularing and restructure the dashboard plugin using React.