go.mod: upgrade wireguard-windows, de-fork wireguard-go

Pull in the latest version of wireguard-windows.

Switch to upstream wireguard-go.
This requires reverting all of our import paths.

Unfortunately, this has to happen at the same time.
The wireguard-go change is very low risk,
as that commit matches our fork almost exactly.
(The only changes are import paths, CI files, and a go.mod entry.)
So if there are issues as a result of this commit,
the first place to look is wireguard-windows changes.

Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>

wgengine/router/ifconfig_windows.go

@@ -17,8 +17,8 @@ import (
 
 	"github.com/go-multierror/multierror"
 	ole "github.com/go-ole/go-ole"
-	"github.com/tailscale/wireguard-go/tun"
 	"golang.org/x/sys/windows"
+	"golang.zx2c4.com/wireguard/tun"
 	"golang.zx2c4.com/wireguard/windows/tunnel/winipcfg"
 	"inet.af/netaddr"
 	"tailscale.com/health"

wgengine/router/router.go

@@ -7,7 +7,7 @@
 package router
 
 import (
-	"github.com/tailscale/wireguard-go/tun"
+	"golang.zx2c4.com/wireguard/tun"
 	"inet.af/netaddr"
 	"tailscale.com/types/logger"
 	"tailscale.com/types/preftype"

wgengine/router/router_darwin.go

@@ -5,7 +5,7 @@
 package router
 
 import (
-	"github.com/tailscale/wireguard-go/tun"
+	"golang.zx2c4.com/wireguard/tun"
 	"tailscale.com/types/logger"
 )
 

wgengine/router/router_default.go

@@ -7,7 +7,7 @@
 package router
 
 import (
-	"github.com/tailscale/wireguard-go/tun"
+	"golang.zx2c4.com/wireguard/tun"
 	"tailscale.com/types/logger"
 )
 

wgengine/router/router_freebsd.go

@@ -5,7 +5,7 @@
 package router
 
 import (
-	"github.com/tailscale/wireguard-go/tun"
+	"golang.zx2c4.com/wireguard/tun"
 	"tailscale.com/types/logger"
 )
 

wgengine/router/router_linux.go

@@ -16,7 +16,7 @@ import (
 
 	"github.com/coreos/go-iptables/iptables"
 	"github.com/go-multierror/multierror"
-	"github.com/tailscale/wireguard-go/tun"
+	"golang.zx2c4.com/wireguard/tun"
 	"inet.af/netaddr"
 	"tailscale.com/net/tsaddr"
 	"tailscale.com/types/logger"

wgengine/router/router_linux_test.go

@@ -16,7 +16,7 @@ import (
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
-	"github.com/tailscale/wireguard-go/tun"
+	"golang.zx2c4.com/wireguard/tun"
 	"inet.af/netaddr"
 )
 

wgengine/router/router_openbsd.go

@@ -10,7 +10,7 @@ import (
 	"log"
 	"os/exec"
 
-	"github.com/tailscale/wireguard-go/tun"
+	"golang.zx2c4.com/wireguard/tun"
 	"inet.af/netaddr"
 	"tailscale.com/types/logger"
 )

wgengine/router/router_userspace_bsd.go

@@ -12,7 +12,7 @@ import (
 	"os/exec"
 	"runtime"
 
-	"github.com/tailscale/wireguard-go/tun"
+	"golang.zx2c4.com/wireguard/tun"
 	"inet.af/netaddr"
 	"tailscale.com/net/tsaddr"
 	"tailscale.com/types/logger"

wgengine/router/router_windows.go

@@ -16,8 +16,8 @@ import (
 	"syscall"
 	"time"
 
-	"github.com/tailscale/wireguard-go/tun"
 	"golang.org/x/sys/windows"
+	"golang.zx2c4.com/wireguard/tun"
 	"golang.zx2c4.com/wireguard/windows/tunnel/winipcfg"
 	"inet.af/netaddr"
 	"tailscale.com/logtail/backoff"