NamedArtifact should default on the base model itself

[paulletang]

Description

Instead of requiring us to use FillRequiredProperties on the inheriting models, we should just default a randomly generated name on the base model.
If this is undesirable for any of the models that inherit from this, they're probably not a typical NamedArtifact, and might need to stop inheriting from that.

Example

Instead of defaulting on FillRequiredProperties, we would default on the NamedArtifact itself.

Desired Behavior

Name is autogenerated if not defined when instantiated.

Current Behavior

Name is null until FillRequiredProperties, which sometimes happens in the API repository, or sometimes not at all!

Why this enhancement would be useful to most Relativity.Testing.Framework users

Consistent and predictable autogeneration of the name property on NamedArtifacts.
We should also continue this paradigm with other stories to include everything that can be defaulted without looking up values.