Add some time series anomaly detection models

[yyysjz1997]

1. Model description

Add some TSAD algorithms into PyPOTS, including but not limited to TimesNet, FEDformer, Reformer, Pyraformer, DLinear, iTransformer, TimeMixer, etc.

2. Check open-source status

• The model implementation is publicly available

3. Provide useful information for the implementation

Please check the original code repo at https://github.com/WenjieDu/PyPOTS?tab=readme-ov-file#-available-algorithms.

4. Your contribution

PR will come later.

[github-actions]

Hi there 👋,

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Wenjie