[Feature] : Expose key on TimerCountdown

[Vlad-Adrian]

Plugin name
Appinio flutter timer countdown

Is your feature request related to a problem? Please describe.

• you start the timer countdown with expectedTime 1 minute
• you send the app to background
• after the 1 minute, a new timer countdown should start with expectedTime 2 minutes
• the TimerCountdown widget gets blocked/stuck on 0 0 or another weird state, because it doesn't get updated and restarted with the new expectedTime

Describe the solution you'd like
There are multiple solutions to this problem/improvement. Exposing the key on TimerCountdown would be just one of them or this situation could be handled in the TimerCountdown lifecycle.