Make phxWindow.addEventListener optional

[majeed-platogo]

The block below is useful for handling autoconnection/disconnection when users leave or enter the tab

if (phxWindow && phxWindow.addEventListener) {
      phxWindow.addEventListener("pagehide", (_e) => {
        if (this.conn) {
          this.disconnect();
          awaitingConnectionOnPageShow = this.connectClock;
        }
      });
      phxWindow.addEventListener("pageshow", (_e) => {
        if (awaitingConnectionOnPageShow === this.connectClock) {
          awaitingConnectionOnPageShow = null;
          this.connect();
        }
      });
    }

But in our case, It clashes with our own listener that does this among other things. That's why we're introducing disableWindowEventListeners to make this optional