GH-1524 Regenerate Minecraft client token when the auth token is invalid

This makes the case where users copy MultiMC to other machines
easier to handle. It doesn't require manual intervention and the tokens
do not go in a desync loop.

application/LaunchController.cpp

@@ -108,6 +108,7 @@ void LaunchController::login()
 				auto failReasonNew = task->failReason();
 				if(failReasonNew == "Invalid token.")
 				{
+					account->invalidateClientToken();
 					failReason = needLoginAgain;
 				}
 				else failReason = failReasonNew;