[code] notify a user about missing scopes on git actions

[akosyakov]

In Theia user gets prompted if there are NOT enough rights to perform git action like push. We should move this logic to the supervisor and expose the notification API from IDE to the supervisor.

[csweichel]

A notification API would be great. How would that API look like?

service NotificationService {
    rpc Notify(NotifyRequest) returns (NotifyResponse) {}

    rpc Subscribe(stream NotifyResponse) returns (stream NotifyRequest) {}
}

message NotifyRequest {
    string title = 1;
    string message = 2;
    // if actions are empty, Notify will return immediately
    repeated string actions = 3;
}

message NotifyResponse {
    // action chosen by the user
    string action = 1;
}

[akosyakov]

something like that but it should be stream right?

[csweichel]

blocked on #3267