[0.1.0] Refactoring CTGAN for DataLoader

[Wh1isper]

Description

Motivation and Context

• Rewrite CTGAN based on MIT Licensed code
• Imp and test part of Synthesizer
• Intro optimized CTGAN component for DataLoader's chunk read.

How has this been tested?

Types of changes

• Maintenance (no change in code, maintain the project's CI, docs, etc.)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[sweep-ai]

Apply Sweep Rules to your PR?

• Apply: All new business logic should have corresponding unit tests.
• Apply: Refactor large functions to be more modular.
• Apply: Add docstrings to all functions and file headers.

[Wh1isper]

@MooooCat
This PR supports DataLoader on the interface, but does not yet support chunk reading on all model component

I'll draft another PR for lazy ndarray loader for Sampler

Docs is not updated yet, will update all before release.

[Wh1isper]

I believe DataLoader has a lower memory consumption when it is fetching whole columns: https://github.com/hitsz-ids/synthetic-data-generator/blob/0.1.0-ctgan/sdgx/data_loader.py#L106

[MooooCat]

This PR supports DataLoader on the interface, but does not yet support chunk reading on all model component

Sure, we can finish these components one by one, the files changed is enough for this PR.

I may spend a little time running and understanding the new module such as DataLoader, which won't be long.

If we provide some examples of DataLoader or other modules in docs, developers may be able to quickly understand the use of modules.