Add getInitialMessage method for handling push notification in Terminated App State

[vinothvino42]

Ticket: #1027

[vusters]

are you missing some files? You are removing the logic to execute callbacks but added somewhere else?

[vusters]

Here's how you can resolve the race condition:

• in NotificationManager, have init() returns the initial message.
• in main, await for the NotificationManager's init() and retreieve this initial message.
• if the messge has screenId/screenName, pass them into EnsembleApp.

This will ensure the 1st scren you load will be the screenId/screenName you have.

[vinothvino42]

are you missing some files? You are removing the logic to execute callbacks but added somewhere else?

I added it in the screen widget, it's because the ensemble_app fetches the definition and then only it renders the widget. So I just added it in the screen widget, here the material app is already initialized with the definition.

[vinothvino42]

Here's how you can resolve the race condition:

• in NotificationManager, have init() returns the initial message.
• in main, await for the NotificationManager's init() and retreieve this initial message.
• if the messge has screenId/screenName, pass them into EnsembleApp.

This will ensure the 1st scren you load will be the screenId/screenName you have.

I updated the Firebase getInitialMessage and updated the client's main.dart to initialize the app with screen id or name when the app launched from the push notification in the terminated state

[vinothvino42]

@vusters I'll merge this PR