Dynamic Groups with nested object filters like Location don't work in child groups

[jathanism]

Environment

• Nautobot version (Docker tag too if applicable): 1.4.7
• Python version: 3.10
• Database platform, version: n/a
• Middleware(s): n/a

Steps to Reproduce

This is a follow-up to #2665, which fixed the ability for Dynamic Groups to filter properly on nested object types like Location and Region by augmenting TreeNodeMultipleChoiceFilter.filter() to iterate the tree descendants (e.g. Location A --> Location B).

Create Locations

1. Create a LocationType called My Region and content-type dcim | device
2. Create a LocationType called My Site with parent set to LocationType("MyRegion") and content-type dcim | device

3. Create a new Location with LocationType of My Region called Location A with site AMS01 (which is part of the demo dataset)
4. Create a new Location with LocationType of My Region --> MySite called Location B with parent Location A

Create Devices

1. Create a new Device named new-device1 with site AMS01 and location set to Location A
2. Create a new Device named new-device2 with site AMS01 and location set to Location B

Create Dynamic Groups

1. Create a DynamicGroup with a filter for a location = "Location A" named devices-location-a

2. Create a DynamicGroup with an empty filter as a parent group named location-parent
3. Edit location-parent and set the first child group to devices-location-a with operator Include (OR).

Expected Behavior

• Navigate to Dynamic Groups list view
• Observe that devices-location-a has 2 members
• Observe that location-parent also has 2 members

Observed Behavior

• Observe that devices-location-a has 2 members
• Observe that location-parent only has 1 member

What is happening in the workaround from #2665 is:

• DynamicGroup.get_queryset() only uses the filterset to identify membership
• DynamicGroup.get_group_queryset() instead relies on aggregated generated Q() objects derived from all child groups
• DynamicGroup.members was augmented to return get_queryset() if there are no child groups as a workaround to make filtering on tree objects like Location work, as evident in devices-location-2 having 2 members from Location A and Location B (which is a child of Location A)
• Nested Dynamic Groups with children still fallback to the old behavior
• The root cause is in the difference between forward lookup using filtersets (e.g. {"location": ["location-a"]}. This will filter as expected because the TreeNodeMultipleChoiceFilter is doing recursive descent for all child locations...
• Compared to the reverse lookup, which is using generated Q() objects, (e.g. location__slug='location-a') which you can see IS NOT recursively descending. In the case of the location-parent, observe that the correct generated Q object should be (location__slug='location-a' OR location__slug='location-b').

TL;DR

• Simple dynamic groups (no children) use forward filtering based on filtersets
• Advanced dynamic groups (with children) use reverse filtering based on Q objects
• TreeNodeMultipleChoiceFilter needs to be augmented to correctly generate a nested Q object for any descendants using the generate_query() pattern (See: SearchFilter.generate_query()
• DynamicGroup.generate_query_for_filter() needs to be augmented to look for generate_query() methods on Filter instances when it is building nested Q objects for advanced dynamic group. It currently type checks if the filter is an instance of django_filters.MultipleChoiceFilter and calls get_filter_predicate() for each value, but this isn't sufficient for tree node filters.