[Feature Request] Ability to modify connection TTL

Sometimes ISPs enforce restriction on the Internet service based on the operating system which is being used by the customer. For example, if the Mobile network operator detects that the customer is using Windows operating system via tethering, instead of Android, to establish Internet connection, it enforces some limitations on the service.
One way that is used to detect is checking connection TTL. In order to bypass this restriction, something like the following IPTABLES rule can be used:

iptables -t mangle -I POSTROUTING -o wan -j TTL --ttl-set 65

It would be great if this could be done natively by Sing-box. An argument like this is suggested:

{
    "action": "route-options",
    "override_ttl": ""
}

The issue names the route-options action and an iptables POSTROUTING TTL rule, but no repository files or tests. Start by locating route-options configuration handling and the platform-specific networking path; done means a configured TTL can be applied to the relevant traffic and its behavior is covered by the project's available checks.