Closes: #193 - Allow Custom Object Types to specify a group_name for navigation menu grouping

[bctiemann]

Closes: #193

This adds a group_name field to CustomObjectType which allows COTs to be grouped in the navigation menu. An unspecified group_name results in COTs being grouped under "Objects" as before.

Note: This solution requires that NetBox be restarted in order to re-populate the groupings in the nav menu if they have changed. This is because only the list of items within a group is iterable; the groupings themselves are populated concretely at app startup time.

[arthanson]

Failing test for some reason: django.db.utils.ProgrammingError: relation "netbox_custom_objects_customobjecttype" does not exist

[arthanson]

Couple issues:

I had two existing custom object types, I added a a1 group label to the first, b2 to the second one.

1. When I add b2 the custom object in the sidebar disappears - forcing you to restart. I know you stated that it requires a restart to show, but this forces a restart as soon as you add a group name. I don't think that is acceptable, or if okay with PM then should at least have a big warning on the field that you must restart if you change this item - IMHO I wouldn't ship with this restriction.

2. The ordering of the menu items is non-deterministic. Each time you restart the group a1 and b2 can shift places. a1 is first on some restarts, b1 is first on others.

3. Should probably add group-name to filters

I also think there should be some minimal tests:

• A test that a COT with group_name appears in the correct group in get_grouped_menu_items()
• A test that group_name is serialized in the API response

[bctiemann]

@claude /review