Verify that signaling server is online before using it

[jrhea]

What is the best way to handle offline signaling servers?

Does Infura have one we can count on? If not, we eventually need to host our own.

In the meantime, here are the ones that I know protocol labs make available:

/dns4/ws-star-signal-2.servep2p.com/tcp/443/wss/p2p-websocket-star
/dns4/ws-star-signal-1.servep2p.com/tcp/443/wss/p2p-websocket-star
/dns4/ws-star.discovery.libp2p.io/tcp/443/wss/p2p-websocket-star

Tried adding all of them to the Swarm array in hopes that it would fail over to the available one, but it didn't seem to work like that (this needs to be verified though).

Could specifically check (in code) to see which one is online before using it.

Note: In chrome I can navigate to: ws-star-signal-2.servep2p.com to see if it is up and running. This needs to be done in code.