Feat: add a timeout option to Peer

Currently, we can only call failPendingRequests() to make all the pending requests fail.

Sometimes it's better to set a timeout value and let the request failed automatically when it runs time out.

The simplest modification should be to add a timeout argument to failPendingRequests(timeout: number), which can be called period and clean the timeout-ed requests.

A better way to implement it might integrate the timeout with the Peer class.
For example:

interface PeerOptions {
  timeout: number
}

class Peer {
  constructor(public options: PeerOptions) {
  }

  // request will be rejected if it did not get any response from the server after timeout milliseconds.
}

Start by reading the Peer class and the existing failPendingRequests() handling for pending requests. Determine how timeout configuration should be exposed and how timed-out requests are rejected and cleaned up; done means requests without responses fail automatically after the configured milliseconds.