希望能增加邮箱备份配置及数据库功能

### Please make sure of the following things

- [x] I have read the [documentation](https://alist.nn.ci).
- [x] I'm sure there are no duplicate issues or discussions.
- [x] I'm sure this feature is not implemented.
- [x] I'm sure it's a reasonable and popular requirement.

### Description of the feature / 需求描述

希望能增加个功能：可设置自动备份数据库文件和普通备份文件，并发送到指定邮箱。（类似lucky万吉的邮箱备份功能）

### Suggested solution / 实现思路

_No response_

### Additional context / 附件

_No response_