make TailscaleClient interface

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

integration/tailscale.go

@@ -0,0 +1,18 @@
+package integration
+
+import (
+	"net/netip"
+
+	"tailscale.com/ipn/ipnstate"
+)
+
+type TailscaleClient interface {
+	Hostname() string
+	Shutdown() error
+	Version() string
+	Up(loginServer, authKey string) error
+	IPs() ([]netip.Addr, error)
+	Status() (*ipnstate.Status, error)
+	WaitForPeers(expected int) error
+	Ping(ip netip.Addr) error
+}