New analyzer: Unhandled event in Orleans JournaledGrain

[ronnygunawan]

public class FooGrain : JournaledGrain<FooGrainState>, IFooGrain {
    public Task Command1() {
        RaiseEvent(new FooEvent1());
    }

    public Task Command2() {
        RaiseEvent(new FooEvent2());
    }
}

// Warning: Unhandled event: FooEvent2
public class FooGrainState {
    public void Apply(FooEvent1 @event) { }
}

public record FooEvent1;
public record FooEvent2;
public record FooEvent3;