Clarify deprecated parts in `factory.fuzzy`

[rbarrois]

The problem

Some of the features included in factory.fuzzy are now a duplicate of faker-provided items. But some don't have a satisfactory equivalent.

Proposed solution

• Describe what is, and isn't, deprecated;
• Clarify the differences

Extra notes

For instance:

• factory.fuzzy.FuzzyChoice is guaranteed to be lazy, whereas factory.Faker('random_choice', elements=...) isn't — the latter might evaluate a queryset at import time;
• factory.fuzzy.FuzzyDateTime is explicitly timezone-aware, whereas Faker defaults to naive datetime;
• The current API for factory.Faker makes for less readable/IDE-compatible code compared to factory.Fuzzy.

[melvyn-apryl]

Moving forward:

• Generate equivalents based on Faker for those that have them and deprecate them: this would educate and flag for future removal
• Provide alternatives to Faker for things we'd like to behave differently or is non existent
• Finally, remove or shrink fuzzy

Sorry, my proposal (jotting this down before going into a meeting).

[melvyn-apryl]

Faker is harder to use in factory.lazy_attribute, missing a fuzz() that can just be called, especially for types like dates that depend on each other to form a valid period, this is non obvious (still figuring that out).