This patch adds support for manually setting subnets that should be handled as VPN, i.e be subject to VpnPreference, in case webrtc fails to auto-detect VPNs. Bug: webrtc:13097 Change-Id: I42514f0677a35cfe30ad053570fa9c2a5b4a856b Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/230122 Commit-Queue: Jonas Oreland <jonaso@webrtc.org> Reviewed-by: Harald Alvestrand <hta@webrtc.org> Cr-Commit-Position: refs/heads/main@{#34852}