Improve error message for payments

[srirambv]

This site Users will question Which site??

Wouldn't it be simpler to just say Brave Wallet can't be reached, Please check your Internet connection. instead saying an error occurred and showing DNS error message

Also monthly budget dropdown should be disabled and status shouldn't show Your Wallet is ready! when it can't retrieve info. Status should be hidden when the wallet balance is not shown

cc: @mrose17 @bradleyrichter @ayumi

• Related issue
  #4920

[jkup]

I agree with the "This Site" part. I think a more generic error message would be great. As for the disabled fields.. is there a situation you can get into where your wallet is ready and you already have a monthly budget set but we just can't get your balance right now?

I only worry about making the entire feature look disabled when really we're just offline so can't get a real time balance.