* Proxy: TUN: Enhance Darwin interface support.
- reduce number of actions done to create/configure the interface in the system
- assign synthetic static link-local ipv4/ipv6 addresses to the interface, that are required by the OS for the routing to work
- make tun_darwin_endpoint be implemented significantly more similar to tun_windows_enpoint, preparing them for potential unification
* Proxy: TUN: Unify Darwin/Windows endpoint, which are now extremely similar, into one GVisorEndpoint.
Making darwin/windows tun implement GVisorDevice with simple readpacket/writepacket methods that GVisorEndpoint untilise
