Extend DiD Classes

[SvenKlaassen]

Extend did module

Extend DoubleMLData Classes

• create data module
• separate data classes into different files
• create DoubleMLPanelData class

DiD Module

• created did.datasets module including make_did_SZ2020
• added make_did_CS2021 DGP
• added DoubleMLDIDBinary class with flexible periods
• added DoubleMLDIDMulti class for multiple periods

Reference to Issues or PRs

• Sensitivity rework Rework the DID Sensitvitiy  #262 (added warnings for benchmarks and updated docs)

Comments

Compare to

• main...p-did-ext

PR Checklist

• The title of the pull request summarizes the changes made.
• The PR contains a detailed description of all changes and additions.
• References to related issues or PRs are added.
• The code passes all (unit) tests.
• Enhancements or new feature are equipped with unit tests.
• The changes adhere to the PEP8 standards.

[PhilippBach]

Hi @SvenKlaassen
I realized that there's an issue when calling plot_effects() for only one treatment group, see #315

[PhilippBach]

Thanks for the PR. The changes look good to me.