Feat/update __init__.py for 3w dataset 2.0

[castrokelly]

This pull request updates the __init__.py file to ensure compatibility with the 3W Dataset 2.0 and reflect the changes made in the base.py and dev.py modules.

Changes made:

• Updated toolkit version: Incremented the toolkit version to 1.2.0 to reflect the significant changes introduced for 3W Dataset 2.0 compatibility.
• Imported and exposed load_3w_dataset: The new load_3w_dataset function, which is designed to handle the 3W Dataset 2.0, is now imported and exposed through the __init__.py file. This makes the function readily available for users of the toolkit.

Improvements:

• Compatibility: The updated __init__.py ensures that the 3W Toolkit is compatible with the latest version of the 3W Dataset.
• Ease of use: The load_3w_dataset function is now easily accessible, allowing users to load the 3W Dataset 2.0 directly without needing to import it from a specific submodule.

Example usage:

import toolkit as tk

# Load the real data from the 3W Dataset 2.0
df = tk.load_3w_dataset(data_type='real', base_path='path/to/dataset')

This update streamlines the usage of the 3W Toolkit with the 3W Dataset 2.0, making it easier for users to load and analyze the data.

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