Re-focus the popup between requests

It's possible for a user to leave the popup open between requests, especially after onboarding when the popup is not closed programmatically. Because of this, when a new request comes through, the popup doesn't re-focus itself and updates in the background. This leads to a bad UX since the user can't see the popup and has to manually re open it.
- This PR simply calls popup.focus() every time a new request comes to an already open popup. This ensures that the popup doesn't stay hidden in the background when a user performs an action on a dapp

coinbase / coinbase-wallet-sdk