Support tracking data

[jo-mueller]

Fixes #381, relevant for #376

This pull request introduces support for a new dataset, tgmm_mini_dataset, and adds functionality for handling Tracks layers in the napari_clusters_plotter plugin. The most important changes include adding the new dataset, updating the widget to handle Tracks layers, and enhancing tests to cover the new dataset and layer type.

New Dataset Support:

• Added tgmm_mini_dataset function to load the TGMM mini dataset in src/napari_clusters_plotter/_sample_data.py.
• Updated __init__.py to include tgmm_mini_dataset in the module exports.
• Updated napari.yaml to include the new dataset under contributions. [1] [2]

Tracks Layer Support:

• Modified _algorithm_widget.py to import and handle Tracks layers. [1] [2]
• Updated _new_plotter_widget.py to connect Tracks layer properties and apply colors to Tracks layers. [1] [2]

Testing Enhancements:

• Added tests for the new tgmm_mini_dataset in test_sample_data.py. [1] [2]
• Added create_multi_tracks_layer function and updated existing tests to include Tracks layers in test_plotter.py. [1] [2] [3]

Documentation and Licensing:

• Added a LICENSE file for the TGMM mini dataset.
• Added a README.md for the TGMM mini dataset.

cc @stefanhahmann