Popup for when wargoal is not included in peace offer

[Slayen]

My suggestion is exactly what it says on the tin.

When you are fighting a war for with a specific war goal, it would be nice if there was a pop up that would appear should accidentally send out a peace off without said goal.

I've now had two ironman games come to a screeching halt due to peacing out without actually taking the provinces I needed and feel that this would just make for a nice QoL improvment.