Update the Event Flushing Mechanism to save in disk

[CoderGamester]

Update the Event Flushing Mechanism to avoid losing events due to network issues or game being closed

• Add the option to save events to disk if they failed to be sent when the game loses focus on the device screen.
• Disable sending events if application is offline
• Added Task return to allow methods to await for event flushing to be done. This is useful in the case events fail and are needed to save localy

Reasoning

• I noticed that the SDK doesn't have "offline" or "lose connection" mode this means that failed events would never be sent if the device lose connection at the end of the session or the player plays the entire session offline
• This is not optimal for mobile games or low stable network devices