feat: add umask configuration support

[wanglu-cell]

Which issue(s) this PR fixes:
Fixes #

What this PR does / why we need it:
增加 umask 配置支持，使日志文件权限控制更灵活。当用户需要指定非默认文件权限时，可通过配置 umask 参数实现。
Docs Changes:
无
Release Note:
新增功能: 支持通过 umask 参数控制输出文件权限

[daipom]

Thanks for your contribution!

Could you please clarify what this PR does?

Fluentd already has umask command line option.

• https://docs.fluentd.org/deployment/command-line-option

The limitation of this option is:

• There is no system config option yet.
• It works only when using --daemon or --no-supervisor.
  • For example, it does not work when using Docker.