feat: a possible better way to enter password

[stceum]

• 一种可能更好的输入密码的方式。

  之前：（需要密码，该密码可能存在于 bash/zsh/... 历史记录中）：

  $ ipgw config account add -u xxxxxxx -p xxx...xxx # 可能不安全

  现在：

  $ ipgw config account add -u xxxxxxx
  Enter Password: # 输入时不回显

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• A possible better way to enter password.

  previous (password is required which may exist in the bash/zsh/... history):

  $ ipgw config account add -u xxxxxxx -p xxx...xxx # Potentially unsafe

  current:

  $ ipgw config account add -u xxxxxxx
  Enter Password: # type in without echo