##### SUMMARY
Customer request: When typing the string to encrypt, it shows up as plain text. Since the string is being encrypted, it's safe to assume that it's sensitive (e.g. passwords) and should therefore be hidden. At the very least, maybe this could be a command line option. If it is hidden, I'd prefer to be forced to enter it twice to avoid mismatch. To mitigate this issue, I am currently using "stty -echo", but that shouldn't be necessary.

##### ISSUE TYPE
- Feature Idea

##### COMPONENT NAME
ansible-vault
stderr=True)
                display.display('The last named variable will be "%s". The rest will not have'
                                ' names.' % context.CLIARGS['encrypt_string_names'][-1],
                                stderr=True)
            
            for extra_arg in args[len(name_and_text_list):]:
                name_and_text_list.append((None, extra_arg))
        
        else:
            name_and_text_list = [(None, x) for x in args]
        
        for name_and_text in name_and_text_list:
            name, plaintext = name_and_text
            if plaintext == '':
                raise AnsibleOptionsError('The plaintext provided from the command line args was empty, not encrypting')
            b_plaintext = to_bytes(plaintext)
            b_plaintext_list.append((b_plaintext, self.FROM_ARGS, name))
        
        
        outputs = self._format_output_vault_strings(b_plaintext_list, vault_id=self.encrypt_vault_id)
        for output in outputs:
            err = output.get('err', None)
            out = output.get('out', '')
            if err:
                sys.stderr.write(err)
            print(out)
        if sys.stdout.isatty():
            display.display("Encryption successful", stderr=True)
        
    def _format_output_vault_strings(self, b_plaintext_list, vault_id=None):