Rename recursion level Enum and values

[Arithmomaniac]

@brycekbargar proposed the following instead of the current names/values for ObjectFieldsDepthLevel:

ObjectFieldsBehavior.NoRecursion
ObjectFieldsBehavior.ShallowRecursion
ObjectFieldsBehavior.FullRecursion

I like it.
After Fest, we can add these, and flag the ObjectFieldsDepthLevel as [Obsolete] (they would still work, as we could cast to ObjectFieldsBehavior type.). Eventually, we would be able to remove them.

[KalinaTSD]

This is something minor. It will be implemented by me.