NeoFS CLI input credentials

[alexvanin]

NeoFS CLI help command suggests to pass WIF, hex or wallet file to get private key.

$ neofs-cli --help
...
Flags:
...
  -k, --key --key new         private key in hex, WIF, NEP-2 or filepath (use --key new to generate key for request)

However after #562 it is not true. I suggest to keep support of WIF or hex encoded files, but we can do that in different arguments (the same way as NEOFS_KEY and NEOFS_WALLET are the same arguments in storage node config).

[alexvanin]

My proposal to have these arguments used in such priority:

--generated-key                 // generates new private key in runtime
--wif <WIF>                     // expects string with WIF
--binary-key <path>             // expects 32 byte binary file
--wallet -w <path>              // expects path to NEP-2 or NEP-6 wallet file
--address -a <wallet-address>   // used with `--wallet`

You can change naming as you want, though.