Fix DynamicGroup Serialization Bug

[bryanculver]

Closes: #DNE

What's Changed

Worked with @lampwins to reproduce this bug.

TLDR: When a Dynamic Group is being saved, there is an edge case where a Filter Form and a FilterSet Form are not identical. A way to reproduce this is with: https://github.com/nautobot/nautobot/tree/u/bryanculver-dg-bug and creating the necessary relationship to filter on it. What happened is the nested filter through the relationship and ultimately is filtering on the name of an FK, the FilterSet Form expects inputs to be a list of strings (it's a MultiValueCharFilter after all). But for UX we want to have a selection of names of object instances. We can do this by using the to_field_name and processing accordingly. We have logic in Dynamic Groups that does this if the FilterSetForm filed is of the right type. The FilterForm is helping us to this today, but the FilterSetForms need some work to be returning/use the smarter Form field types.

This fix allows to use the FilterForm field first if it's available and falls back if it's not.

Special handling had to be done for Tags because our Tag filter form field isn't a ModelMultipleChoiceField; the FilterSetForm field before was using a ModelMultipleChoiceField.

I'm open to ideas on how to write a test for this which doesn't require a bunch of complex setup like in the branch referenced above.

TODO

• Explanation of Change(s)
• Added change log fragment(s) (for more information see the documentation)
• Attached Screenshots, Payload Example
• Unit, Integration Tests
• Documentation Updates (when adding/changing features)
• Example Plugin Updates (when adding/changing features)
• Outline Remaining Work, Constraints from Design

[glennmatthews]

Would it make sense to add a unit/integration test to check for this bug?

[glennmatthews]

Needs change fragment, otherwise looks solid.