add auto differences

[jmoralez]

Description

Adds the following target transformations:

• AutoDifferences: Determine and apply optimal number of single differences
• AutoSeasonalDifferences: Determine and apply optimal number of differences for a fixed seasonal period
• AutoSeasonalityAndDifferences: Determine the length of the seasonal period and take that difference

Checklist:

• [x] This PR has a meaningful title and a clear description.
• [x] The tests pass.
• [x] All linting tasks pass.
• [x] The notebooks are clean.

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