`NautobotModel.get_from_db()` doesn't work for custom fields and many to many relationships

[Kircheneer]

Environment

• Python version:
• Nautobot version: 1/2
• nautobot-ssot version: 1.6/2.0

Expected Behavior

When defining a model like this:

from typing import Annotated

from nautobot.tenancy.models import Tenant

from nautobot_ssot.contrib import NautobotModel, CustomFieldAnnotation

class TenantModel(NautobotModel):
    _model = Tenant
    _modelname = "tenant"
    _identifiers = ("name", "line_of_business",)

    name: str
    line_of_business: Annotated[str, CustomFieldAnnotation(name="Line of Business")]

I expect TenantModel.get_from_db() to still work. However, it will issue a query like Tenant.objects.get(name="example", line_of_business="Shipping") which will crash. Instead, we should use the mapping from the CustomFieldAnnotation.

Observed Behavior

There is a crash, because the field line_of_business doesn't exist.

Steps to Reproduce

Described above.

[Kircheneer]

Fixed for custom fields with #350

[Kircheneer]

Also, #361