solana: `solana stakes <vote pubkey>` should cleanly handle a non-vote pubkey

`solana stakes <identity pubkey>` or `solana stakes <does not exist pubkey>` all silently return nothing. Lets: * If possible make `solana stakes <identity pubkey>` report the stakes from the corresponding vote account * `solana stakes <does not exist pubkey>` report that the account was not found * `solana stakes <some other account pubkey>` report that the account is invalid