[feature] Provide visual feedback for relay connected/disconnected events

[bkrem]

What problem does this new feature solve?

Web3Modal currently doesn't communicate websocket connected/disconnected states to the end user, creating ambiguity when e.g. a QR code is scanned but nothing happens on the wallet (e.g. because the dapp lost or shutdown its WS connection)

Describe the solution you'd like

• Listening for the relayer's RELAYER_EVENTS.connect and RELAYER_EVENTS.disconnect events (docs, example usage)
• Showing a toast or other temporary notification item immediately, that lets the user know that they are no longer connected or are connected again

[bkrem]

cc @ganchoradkov