Fix wslsetupotions being None

Recent changes in GUI turned possible to have that field as None,
leading to a crash.
This avoids the crash while preserving the default behavior of
installing the language packs.

system_setup/server/controllers/configure.py

@@ -225,8 +225,8 @@ class ConfigureController(SubiquityController):
             return True
 
         cmd = []
-        if self.model.wslsetupoptions.wslsetupoptions.\
+        opts = self.model.wslsetupoptions.wslsetupoptions
-                install_language_support_packages is True:
+        if opts is None or opts.install_language_support_packages is True:
             cmd = [aptCommand, "install", "-y"]
 
         else: