Support noEncap mode on Windows

[anfernee]

Describe the problem/challenge you have
Running antrea-agent with option TrafficEncapMode: NoEncap will fail with the error:

F1208 05:08:06.203391   11180 main.go:55] Failed to validate: unsupported features on Windows: {TrafficEncapMode: NoEncap}

Describe the solution you'd like
NoEncap mode also works on windows

Anything else you would like to add?
This gives the feature parity to Linux nodes. It will be useful for customers that don't like the performance penalty of an additional tunnel, as well as the MTU implication.

[ruicao93]

Thanks Yongkun for your report. NoEncap mode support on Windows is indeed high priority.

We're working on that but is blocked by an OVS issue: openvswitch/ovs-issues#197

Will address the issue soon with OVS team.

[anfernee]

Thanks @ruicao93 Do you have a rough estimation when it can be done?