show the initial screen if any screens are interactive

the idea here is to stop multiple subiquitys from trampling on each other

subiquity/controllers/welcome.py

@@ -29,6 +29,9 @@ class WelcomeController(SubiquityController):
     autoinstall_schema = {'type': 'string'}
     autoinstall_default = 'en_US.UTF-8'
 
+    def interactive(self):
+        return self.app.interactive()
+
     def load_autoinstall_data(self, data):
         os.environ["LANG"] = data