fix: make command line aliases work again (#564)

This was broken by an unintentionally removed line in 0d11ffc.

Fixes #550

Author: mariobuikhuizen

jupyter_server/extension/application.py

@@ -492,6 +492,7 @@ def initialize_server(cls, argv=[], load_other_extensions=True, **kwargs):
             find_extensions = False
         serverapp = ServerApp.instance(
             jpserver_extensions=jpserver_extensions, **kwargs)
+        serverapp.aliases.update(cls.aliases)
         serverapp.initialize(
             argv=argv,
             starter_extension=cls.name,