Harmonize `bail!` vs `panic!` in the CLI

[thibault-martinez]

          We can definitely `bail`, but I do see some panics in `validator_commands` already. For example

iota/crates/iota/src/validator_commands.rs

Lines 309 to 312 in 466ac82

	IotaKeyPair::Ed25519(account_key) => IotaKeyPair::Ed25519(account_key.copy()),
	_ => panic!(
	"Other account key types supported yet, please use Ed25519 keys for now."
	),

So whatever you think is more consistent for the API. cc: @thibault-martinez

Originally posted by @kodemartin in #5502 (comment)