Feature Request: Add DoH (DNS over HTTPS) Support 功能请求：添加 DoH（HTTPS DNS）支持

[montiego]

Hi, I really appreciate your work on v2rayNG. I would like to suggest adding DoH (DNS over HTTPS) support in the app. This feature could improve privacy and DNS resolution security for users. Thank you for considering this enhancement!
您好，我非常感谢您开发 v2rayNG。我想建议在应用中添加 DoH（通过 HTTPS 的 DNS）支持。此功能可以提高用户的隐私和 DNS 解析安全性。感谢您考虑这个改进！