Sending Email Notification To Added User when Admin Adds User [For private Comunity]

## Is your enhancement request related to a problem? Please describe

As of Now I am letting know via other means that I have created your account. This is your default password.

## Describe the solution you'd like

It would be Nice an email trigger from the system to newly added user email address. For first time login credentials

## Describe alternatives you've considered

A clear and concise description of any alternative solutions or features you've considered.

由于 issue 中没有指定文件、测试或入口点，因此请先定位用于添加用户的 admin 流程，以及现有的电子邮件或通知入口点。完成的标准是：对于 private community，新添加的用户会收到一封包含其首次登录凭据的电子邮件，并且对新增行为具有适当的覆盖。

由索引模型根据 Issue 内容生成。