Validate Runtimes notleader not called on all transitions

[anthony-murphy]

notleader should fire in all cases where the client is no longer the leader. inlcuding:

• disconnect
• close
• dispose
• readonly

[vladsud]

It is definitely called on disconnect:

        this.runtime.on("disconnected", () => {
            if (this.runtime.attachState !== AttachState.Detached) {
                this.clearRunningTasks();
            }
        });

Close causes dispose, so the only thing missing is dispose.

[anthony-murphy]

Good to hear. I was unsure of the behavior, and FFX was saying it wasn't working as they expected. I've renamed, as this is more about ensure that all transitions are covered. Ideally, a consumer interested in leader status shouldn't really need to care about other state transitions

[curtisman]

Please add test for all these code path.