NetBird SSH (#361)

This PR adds support for SSH access through the NetBird network
without managing SSH skeys.
NetBird client app has an embedded SSH server (Linux/Mac only) 
and a netbird ssh command.

client/ssh/window_windows.go

@@ -0,0 +1,9 @@
+package ssh
+
+import (
+	"os"
+)
+
+func setWinSize(file *os.File, width, height int) {
+
+}