Add support for JSON request in HTTP test class

"urllib.parse.urlencode()" brokes JSON request's data.

Fixes: https://pagure.io/freeipa/issue/7559
Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>
Reviewed-By: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Petr Vobornik <pvoborni@redhat.com>

ipatests/test_ipaserver/httptest.py

@@ -41,6 +41,7 @@ class Unauthorized_HTTP_test(object):
         :param key When not None, overrides default app_uri
         """
         if params is not None:
+            if self.content_type == 'application/x-www-form-urlencoded':
                 # urlencode *can* take two arguments
                 # pylint: disable=too-many-function-args
                 params = urllib.parse.urlencode(params, True)