Not treating BroadcastOptions.except as optional in all cases

[Inspiravetion]

I found an old issue that fixed this issue for broadcast() and other scenarios but fetchSockets(), addSockets(), delSockets(), and disconnectSockets() are still using the old pattern so the following code:

const existingSockets = await this.adapter.fetchSockets({
    rooms: new Set([user.id])
})

throws an error like

UnhandledPromiseRejectionWarning: TypeError: opts.except is not iterable
at RedisAdapter.fetchSockets (/app/backend/node_modules/@socket.io/redis-adapter/dist/index.js:609:34)
...

[darrachequesne]

For future readers: adapter.fetchSockets() is not meant to be used directly, you should use namespace.fetchSockets() instead.

Please reopen if needed.