Allow passing array of subscription tokens into unsubscribe

[Arcanorum]

Would be nice to just pass an array of sub tokens and have them all unsubscribed.

Something like

const subs = [
    PubSub.subscribe(EVENT_1, (msg, data) => {
        ...
    }),
    PubSub.subscribe(EVENT_2, (msg, data) => {
        ...
    }),
    PubSub.subscribe(EVENT_3, (msg, data) => {
        ...
    }),
];

// then later...

PubSub.unsubscribe(subs);

:^)