* cli: add --enable-close flag to create-token which sets its close authority to mint authority
* cli: add support to changing a mint close authority to authorize
* cli: add close-mint, a new command for closing a mint
* cli: update authorize and close-account to go through the token client
* client: change set_authority and close_account to support multisigners
* cli: remove offline args from commands that create accounts
* cli: implement finish_tx, to be a replacement for handle_tx, which branches on the client return
* client: validate a transaction is fully signed before sending over rpc
* client: convert payer from Signer to Arc<dyn Signer> to support cli signers
* client: support nonce mode
* client: change create_mint to be an object method that returns SendTransaction::Output
* client: rename S2 to S everywhere that Token<T, S> is Token<T>