Create an API endpoint to import rules

[frantz45]

Currently the import functionnality is handled by frontend calls.
It uses the official Graylog API. It makes 2 API calls, one to create the rule and one to create the notification.
It would be nice to have a Wizard API endpoint to import a JSON file containing rules.
It would make our Graylog integration easier.
It would also fix the multiple ugly banners which fill all the screen when importing many rules.

[EzLucky]

Yes, it would be great to have a Wizard API endpoint to handle both the rule and the notification, instead of what we are doing now : calling the wizard API to create the rule, and then the graylog API to create the notification.

If it can handle a multiple rules in one JSON it would be even better.